IMPORTANT NOTE: This post is not meant to dissuade anyone from buying an Airstream. We love the design/layout of our Airstream and would consider buying another Airstream in the future. Many of the things we share below are not specific to Airstreams in particular and will apply to any RV you buy.

Sarah and I still love our Airstream trailer, a 2011 25 (foot) FB (front bedroom) Flying Cloud. The main reasons we were attracted to it initially - the layout, the clean modern open feel, and the panoramic windows on both ends - are still things we appreciate to this day.

That being said, if we were starting from scratch, and had an infinite supply of money and time, there are a few things we would change about our trailer. We've compiled this list as we feel it might be helpful to others looking to purchase a trailer or looking for ways of upgrading their existing trailer.

As of this writing, we have owned our Airstream for 29 months, and have been on the road with it 19 months (including the last 7 months full time). We have spent all of that time in the western US, from the rainy Pacific Northwest in fall and spring, to the Mojave and Sonoran deserts in winter and spring, the Colorado Plateau and red rock country in spring and autumn, and the Colorado mountains in summer.

With a handful of exceptions, that time has been spent on public lands, either public campgrounds (National Parks, State Parks, Forest Service, BLM) or dispersed camping (most commonly on BLM or Forest Service land). Much of this list is geared toward improving our experience while dry camping. If you spend or plan on spending a lot of time in full hookup RV parks, then much of this list will not be relevant.

These items range from "cheap upgrades that we should have already made by now" to massive pie-in-the-sky-will-never-happen-but-would-be-really-cool. All of them are things one should consider when purchasing a trailer or an RV, regardless of if it is an Airstream. I have divided the list into categories to keep it more manageable.

Heating/Cooling

A chilly morning in Colorado, the next morning would be 16F (good thing we had an electrical hookup to run our furnace!)

Replacement of the furnace/fan heating system with a vent-free propane (or "blue flame") heater (this article explains the difference in detail). The standard heating system in our Airstream uses propane for the heat, and our batteries to power the fan to blow the air through the vents. During colder temperatures, running our furnace fan is by far our number one consumer of battery power. With a vent free heater, no battery power is used, only propane is used. The problem with vent free heaters is they are somewhat tricky to install safely - they need a source of oxygen to work properly. Most come with an oxygen sensor and shut off automatically if the oxygen level is too low. It would be best if the Airstreams were designed with this type of heat system from the ground up.
Furnace Zones (or “why does the bathroom get as many furnace vents as our bedroom?”). Our model of Airstream does not have furnace zones, which means the furnace fan is blowing at night and wasting power keeping areas of the trailer warm that we don't care about (such as the living room or bathroom). We could reduce our battery usage significantly if we were able to turn off heat to 75% of the trailer.
An air conditioner that doesn't require a 30 amp hookup or 3000 watt generator. The 13,500 BTU air conditioner in our Airstream requires 30 amps of power to run - meaning a 2000 watt generator is insufficient (you need a 3000 watt generator or a pair of 2000 watt generators, or a 2000 watt generator and a fancy hybrid inverter), and it also means you can't use if you're driveway camping at a friend's house with a standard 15 amp power supply. A 10,000 BTU air conditioner can run on 15 amps. I would prefer to have two of them, where you could run both on 30 amp shore power, or just one off a 2000 watt generator or 15 amp power supply. Recently Airstream has a "ducted climate control" system that is (thankfully) supposed to be much more quiet which is the other big issue with our air conditioning unit. But it still requires a 30 amp power supply to run.
Four-season support. This isn't going to happen with an Airstream by design, they are three-season aluminum trailers. A four-season trailer means a better insulation, so that 20 degree temperatures aren't as uncomfortable and don't lead to condensation everywhere. A four-season trailer also means that holding tanks, valves, and plumbing lines are sufficiently insulated so that they would never freeze at any temperature, eliminating the need to winterize the trailer (which we have done at least a half dozen times in less than three years). While this won't ever happen with an Airstream trailer, other trailers do have this support and it's something to think about if you will be traveling in (or in and out of) cold temperatures.
Heat shielding screens for all skylights and fans. Our Airstream has two ceiling fans, one skylight, and two small windows above the main windows in the living area - and they all can act as a magnifying glass when the the sun is over head - increasing the trailer temperature significantly. We have cut out little heat shields which do help but having something integrated would be preferable.

Electrical/Propane

Higher capacity stock batteries. The default batteries that come with Airstreams are pretty pathetic, two 80-amp-hour 12 volt batteries (meaning 160 amp-hour combined). We replaced with two 220 amp-hour 6 volt golf cart batteries (220 amp-hour combined), which is better but still not ideal.
A larger battery box - in order to put in larger batteries the battery box on our Airstream had to be enlarged - by only 2"! A slightly larger battery box would be able to accommodate larger capacity batteries.
Lithium Ion Batteries. While this is unlikely to be a stock feature any time soon they would be great. Lithium batteries have numerous advantages over lead-acid batteries, namely they're smaller, lighter weight, can be stored unvented indoors, have a higher usability capacity of 80% vs. 60% for lead-acid, can charge more quickly, and support higher amp draws. See the excellent resources at Technomadia for more on lithium batteries.
A built in battery monitor. It baffles me that this isn't a standard feature! Not having a battery monitor is like driving a car without a fuel gage. Sure you can "estimate" the capacity of the battery based on the current voltage reading, much as you can estimate how much gas is left by how many miles you drove since you filled up, but that's imperfect (hills, speed, driving style and other factors affect your fuel efficiency, just like temperature, amp draw, and battery type affect your battery voltage). The only way to really know how much capacity is left is to keep a running tally of how many amps have physically been depleted (or added) since the battery was fully charged (something a mere voltage reading cannot do).
Solar pre wiring that uses larger gage wire. Currently the Airstream "solar pre-wire" uses 10 gage wire, which leads to unacceptable voltage drop if you have more than 1-200 watts of solar panel. This is another baffling "cost-cutting" measure, installing thicker gage wire at the beginning is so much cheaper and functional than having to rip it out after the fact.
More 12 volt outlets. This very possibly could have changed with newer model Airstreams, but there should be a 12-volt DC outlet everywhere there's a 120-volt AC outlet, and all 12-volt outlets should also have USB outlets (USB-C if you're thinking longer term).
An inverter! Airstream models have inverters as options - our particular Airstream does not have one and it would be useful. An inverter allows you to run AC appliances off of the battery (DC) system (in other words, the AC outlets can be powered by the battery). Right now to charge our laptops we use a car-charger adapters but these are flakey. We use a normal cigarette adapter car inverter to charge our camera batteries. If you have the option, getting an inverter to begin with would be good as they are expensive to install later. Also a hybrid-inverters are becoming more common, they can combine the power from a generator and batteries to allow you to run higher current devices (like an air conditioner or microwave) than you would be able to run just off of a generator alone.
A propane quick connect for an outdoor grill. This is something that can be installed after the fact but it would be nice for it to be standard. In practice we just use the little green propane tanks as it gives us much more flexibility on where we can place the grill outside, the ideal location which varies quite a bit depending on the actual campsite.
Ability to have a large amount of solar (> 400 watts) and battery (> 400 amp-hours, preferably lithium) as standard options. We do quite well with our Zamp Solar 200 watt portable panel, but would prefer 500 watts of fixed solar to help us through stretches of overcast weather without having to fire the generator.
Fantastic fans - they work but they are so loud! Having quieter fans would be great.

Water/Sewer

Dry camping just outside of Capitol Reef National Park

Gray/Fresh/Black Tank monitors that are actually accurate. Some of this can be due to dirty tanks, but ours are so wildly inaccurate that they're almost unusable. It is possible that the tank monitors in newer Airstreams are more accurate.
Faster tank monitors. Our tank monitor takes 20 seconds to initialize and another 20 seconds to fully cycle through each tank. Can you tell I don't like our tank monitors?
Composting toilet. Now this might sound disgusting, but composting toilets solve multiple problems. They eliminate the need to ever drain a black tank (as you wouldn't use a black tank, though you do have to drain urine). They would free up black tank capacity for gray tank capacity (you can "link" the two tanks fairly easily so that they equalize/level-out). They also don't require water to flush, and don't require tank chemicals (so they are better for the environment). See the excellent article at Gone with the Wynns on composting toilets. When dry camping, it is easy to add water (using 6-gallon water tanks) , it is easy to add electricity (via a generator or solar panels), but it is hard to empty your gray and black tanks (you could get a so-called Blue Boy - but they are often impractical, either too heavy or too small). A composting toilet makes it easy to dispose of waste in a clean way without actually having to move your trailer. They also don't smell!
Larger gray tank capacity. Our Airstream has a 39-gallon fresh tank, a 39-gallon black tank, and a 39-gallon gray tank. Our gray tank always reaches capacity before our black tank. Having the ratio be 2/3 gray to 1/3 black would be more practical (or just using a composting toilet per above and combining the black and gray tanks into a 78-gallon gray tank).
A "cold water return" for the fresh tank. When taking a shower, there is often at least a gallon of cold water in the plumbing lines before the hot water emerges. It would be great to have a non-manual way to put this back in the fresh tank.
Hot water heater tank drain system that isn’t stupid! The only time you really need to drain the water heater is when winterizing, so this isn't a big deal for daily use, but the current system on our airstream involves unscrewing a nylon screw and watching the hot water spill out in random directions everywhere. If that was replaced with a valve that had a hose fitting on the end it would be so much more functional and a lot cleaner.
The black tank flush valve is located directly above the city water inlet valve. If you're careful, this isn't a big deal, but they should be side-to-side rather than on top of each other. Whenever something says "black tank" it should generally be far away from the thing that says fresh water" don't you think?
Airstreams should come standard with a hot water bypass and a pump winterizer kit - both of these are used to winterize the trailer with RV anti-freeze. Ours fortunately did have these installed.
Quiet water pump installation. Our water pump is obnoxiously loud. Two things that would help are a water pump silencing kit (basically using flexible hose instead of pipe), and a pre-pressurized accumulator which eliminates the need to run the pump for doing things like rinsing hands. Speaking of the water pump, we don't need a high gallons per minute pump. Usually the only reason that would be needed that is if multiple water sources are being used simultaneously, such as washing dishes and using the shower. If a lower GPM would use power to pressurize or be quieter (I assume this is true, at least to a small degree, but I am not sure), we would rather have that.
Default shower head which uses less gallons per minute, We installed an Oxygenics shower head which uses less gallons per minute than the stock showerhead, but it should probably be the stock showerhead!
A better kitchen faucet. The kitchen faucet that came with our trailer was fixed, meaning we couldn't swivel it out of the way to fully access the sink basin, so we installed a different faucet.

Build Quality

Use of standard fixtures for cabinet latches, hinges, plumbing, etc. It's really a pain to find replacement latches and hinges (which unfortunately do break). By a pain I mean they're not at a standard hardware store and you have to special order them online.
Light weight mirror above bathroom. The mirror above the bathroom weighs at least 10 lbs. (possibly more), and ours became partially detached (fortunately we noticed before it came crashing down through the toilet!). There is absolutely no reason that this mirror in the bathroom needs to be so heavy! We had to remove ours entirely as it was a hazard waiting to happen. The bonus is I don't have to look at myself anymore!
Wood that is less subject to warping. One thing that is great about traveling in a trailer is the ability to see different places, but those different places often have different climates and different humidity levels. The wood used in our Airstream is subject to heavy warping, some of this could be mitigated by using multiple drawers instead of a long drawer, or using a different material.
Eliminate or improve rounded cabinets. The rounded cabinet under our sink looks really good but is somewhat impractical (both in terms of creating an awkward sized storage area, and because it is difficult to align correctly if there is any warping in the wood).
Better quality foam mattresses. The stock mattress is pretty bad! We have a memory foam topper which helps.
Better quality foam cushions. Memory foam cushions would be more expensive but they would sure feel a lot better. Working for hours on the standard cushions is not good for my back.
Windows can get stuck closed when wet. If there is interior condensation or exterior moisture, the windows can stick and someone has to go outside and loosely pry them free. Apparently baby powder on the outside perimeter of the window can help this, but being as I am a grown man who doesn't (yet!) need diapers I don't think I should have to purchase baby powder to have working windows!
Better quality assurance overall. There are some rivets that are missing, cabinets that could be more securely latched, and overall some shoddy workmanship that really has no place in a premium trailer. If you buy new pay attention to these things and get them fixed under warranty. Regardless, it's a good idea to verify all your screws are secure before heading off to a new spot.
A door latch lock that doesn't randomly lock. Our trailer door has a deadbolt lock and a door latch lock (which we never use) - and the door latch lock can become locked unintentionally just by shutting the door, making it very possible to lock yourself out of the trailer. I instinctually reach for the keys whenever I go outside, and have had the door latch lock itself at least a dozen different times. It's not uncommon either from reading forums. This is an inexcusable bad design. For this reason it is a good idea to keep your spare set of Airstream keys outside the Airstream in some place more accessible (such as your tow vehicle).

Misc

A blazing sunrise outside of Zion National Park

Our trailer comes with a "microwave" upgrade - but to use it you have to be on shore power. We would much prefer the standard (and cheaper) propane oven. The less things that we have to run on shore power the better. Just because they say it's an "upgrade" doesn't mean it is. It all depends on how you use your trailer.
Battery powered fridge. While we haven't had this happen in practice, it would be good to be able to run the fridge on battery power in addition to propane, should the propane run out, or if you are concerned about leaving the propane on while moving sites (we aren't, usually).
A backup camera. These can be installed after the fact but it would be nice to have when driving and backing into a campsite.
OceanAir blinds. The "standard" venetian blinds are not great, the little clips that hold them into place break easily (though fortunately they are a standard part that you can get at any RV store). The venetian blinds also make attractive noise makers for your cat when they want fed at 3AM. The venetian blind behind our bed specifically is annoying as we can't lean against it without it rolled up.
A magnetic fridge! I admit this one isn't super important... but we like to purchase magnets mementos for the various parks and places we visit. The Dometic fridge we have is not magnetic. Neither is any of the aluminum interior. In fact for a metal trailer there is surprisingly little surface area that is magnetic.

After going through that list you might think we are unhappy with our trailer - but you would be wrong! We love the freedom and flexibility that our trailer gives us, but there are a lot of small things (and a handful of big things) that could be changed to make it a better experience.

If you have any annoyances about your trailer (Airstream or not) that we missed, or any comments at all, please let us know below!