QRTRHRS,
I'm with you on the steel trailers. I like the looks of the aluminum trailers and the people who own them say they are the best thing since cold Dr. Pepper, but I am always looking for the longest-life product possible. Given the amount of effort we put into making aircraft aluminum capable of surviving the elements, I wonder how long those shiny beasts will be structurally sound with only a thin clear coat (if anything) on most of them.
The living quarters seem to be most useful as an air conditioned place to change, rest between rounds in competition, etc. Have seen a few of them used by the dedicated trail riders very effectively for camping, but in general if you go to the rodeo grounds or race tracks here in Texas in the summer time you will see a lot of nice trailers with A/C on the roof sitting out in the sun... . with no genset running. Doh!
Drove by the Johnson County Sheriff's Posse arena last weekend, they had a big barrel racing event going and nice aluminum trailers outnumbered the steel variants about 3 to 1. Lots of Sooners, 4 Stars, and a brand called "Elite" I think. The Elites were nice looking trailers but I haven't heard much about them.
Trailer fads come and go every 15 years or so it seems. In the 70's down here those Miley inline horse trailers were THE THING, and when you saw somebody tooling up in a Chevy dually with a powder-blue Miley with dark pinstriping you knew he was a serious horseman

.
One fad I enjoyed and wish would come back is the Urban Cowboy style, "tumbleweed" type hats. They were made out of a very coarse weave jute or something, lots of space for the wind to blow through. BOY those hats were great in the summer time. Sure would like to have one again but never see them for sale.