Pretty sure the rubber roof is the most common trailer roof on the market at this time. Most last around 15 years with basic care.
Trailers/Coaches come in different levels of finish. Depending upon you budget I'd guess I'd look for a brand with respected construction and then see what level of finish my budget and/or I desired.
Break it into pieces or steps and take it one step at a time.
1- determine what you want to do with it. National and State Parks have size limitations. Will you have hook ups or need bigger tanks to be off the grid? Bunkroom models are great if you have kids. Are you taking any toys (motorcycles, ATV's, golf cart?)
2- determine coach, 5th wheel or travel trailer. The last two need a tow vehicle but the coach may need a towed car (toad) for sight seeing.
3- determine new or used. Personal choice and budget.
4- pick a floor plan. Sit in the chairs, lay down on the beds, pretend to live in it. Stand in the shower and go through the motions and same in the kitchen. Can you all move around in it. Can you access what you need to while the slides are in? Some people like to stop for lunch and use the restroom and opening a slide is not an option.
5- where will you store it? Will it fit?
Hope that helps.