As mountainsam said:"For long trips avoid a unit with only a couch and dinette to sit on. They both get pretty uncomfortable on rain days. We are in the process of finding a couple nice recliners or swivel chairs to replace the couch."
I agree with that very much in the TT we had before we didn't have chairs and its not comfortable sitting but now with the 5th wheel the chairs are great.
I personally never cared for a trailer to long, we have 32' and that works nice for us. Just makes it easier to get around with that size 5th wheel.