We are just starting our third week traveling with our TW, doing much the same trip we did last year (so far).
Our FC and TW are set up similarly - twin beds, the FC has just a toilet in the bathroom along the street side about 72" from the back, where the TW has the full bath across the back. The FC is fully converted to 12v/110v where the TW is still a work in progress. Both single axle, both with dinette.
Size difference is noticeable immediately. The TW is 30" longer, 4" wider and 5" taller. It weighs about 600 pounds more. The FC has built in gray 20gal, black 22 gal, and potable water 33 gal. It has no belly pan, the TW has its original, a small original black tank and no gray (I'm using a blueboy portable - not fond of this and will change it in the spring). It has a 50 gal potable water tank installed by the previous owner.
They both work quite well for living in for extended road trips. The big advantage for us with the TW is that we have a vintage cat who travels with us and the larger bathroom allows us to have his food and litter in there and still have room to use the toilet and sink without any noticeable lack of room.
In terms of towing (so far just towed the TW with the '05 Silverado, not the '57 Pontiac wagon - that will happen this spring/summer/fall), is other than climbing long hills the truck will slow down from 65 to 50 towing the TW without downshifting where as the truck just continues without shifting down as often, or slowing down as much. Fuel comsumption is down 4/10ths of a mile if my onboard computer is accurate and it seems to be about right given the distances we can go from tank to tank.
No noticeable difference with wind - still don't feel it, semi's passing are not an event as they have been for friends of ours towing their new SOB last year on this trip.
But just that little bit of added room is nice - it is not much but it feels like more. It is the height inside more than anything.
Sure am having fun. Getting lots of comments in various CG's about it. Both are shiny sort-of-polished but not really, just kept clean and were polished too long ago to count, the TW has dark tint on the windows and I turfed the non-working factory installed A/C unit shortly after buying the TW.
Now that we know the TW works as well for us as the FC has for the past six years, I guess we will sell the FC this spring when we get home, get it cleaned up from winter storage, and give it one last sanity check on whether to keep it to tow behind the '57, or just tow the TW with both. I do notice one thing - the slightly longer TW has forced me to improve my backing up/parking skills. The FC just slides in to any spot like a glove, this one you have to really watch for things above and on either side, and behind, very closely. In the past we never had to think about a CG site size, now we do.
One other note: we have seen a LOT of Airstreams on the road this year, far more than we did the whole trip last year and we are only into the first little bit of our trip. Many on the roads, many on various dealers lots (SOB dealers), many in yards looking like they need a home and more than that on driveways looking like they are ready to hit the road any time for anywhere - as it should be
Life is good, hope you all have a wonderful 2012.