Avoid anything with a slide-out.

Airstreams are worth the extra money for those who want the best. For many years I had a 1958 Airstream 18-footer. Towed it from Baja, California to British Columbia. Now have a 1967 Silver Streak (similar look and construction, built by ex-Airstream people) 24-footer. The quality of these trailers is head and shoulders above the others. The size range you are looking at should be plenty for a couple. The bigger it is, the bigger the tow vehicle necessary.

Mine is like the one pictured.
[Linked Image from silverstreakforsale.files.wordpress.com]

"There's more to optics than meets the eye."--anon

"...most of us would be better off losing half a pound around the waist than half a pound on our rifle."--dhg