With the interior of the '67 Overlander mostly in my micro-shop, it's fun to see how much space there is inside. Our Airstream has the floor plan with a "double" bed amidships and a front gaucho that looks about as comfortable as an iron maiden.
Overall, I think the floor plan is very good... but that hasn't kept me from wondering if it might be improved. We have no need to sleep four, or even three, but we do need a very comfortable "near queen" bed for my wife and me. I can't imagine needing a three-burner cook-top; two seems plenty. I think a microwave would receive far more use than an oven. While we may do some boondocking, the bathroom will more of an "emergency use" facility than an everyday shower, shave and shine room. Still, it's nice to be able to turn around in the head, when necessary.
Air conditioning is a must, but I think putting one on the roof 1) reduces the amount of natural light; 2) looks funny. It would be nice to preserve a more open sense of light and space, even if it meant sacrificing some storage room. I like the idea of a floor plan that allows two people to have elbow room, e.g., one person can nap while the other posts on the Airforums. I think my wife and I are more comfortable in a relatively clean, uncluttered space. During our "up-to-a-year" hiatus, I'd like to use the tow vehicle for "auxiliary storage" and keep the trailer light. I think good design keeps the weight low and amidships. I like the idea of solar panels for trickle charging batteries.
Advances in electronics offer some interesting options. I like the idea of docking our iPods and having small but very high quality speakers. I like the idea of an LED television and a mini DVD player. We need more outlets, if only to charge the insane number of electronic devices like laptops and cell phones we now carry. So, I'm just thinking out loud about design perfection for a 26' long travel trailer... and your thoughts are certainly welcome.