We were a little bit lucky in that we didn't have a TV. So we looked (and looked and looked) for the best part of two years. Finally this year in Feb we were at the Columbus RV and boat show, walked around a corner, and there "it" was (see my sig). We'd been in enough campers by that time to know in about 10 seconds if a particular camper would work for us and if we liked it.
Somebody else said "you'll know it when you see it". That was true for us but we'd been doing homework for better than a year.
Then once we had the one we wanted I spent another 5 months or so finding a TV that could handle it and pulled the trigger on both within about a week of one another.
It was quite an adventure for us - but the time spent was worth it because we were buying new and did not want to make a mistake and end up having to trade it in in a year or two.
So take your time and really sit in these candidates for awhile, walk around, imagine cooking, sitting on the throne, standing in the shower, laying on the bed... How does the candidate work for you? Then look at features and construction. Does it have heated tanks, power jacks, and on and on. What happened for us was that we naturally started eliminating floor-plans and manufactures and we stared focusing in on just a few which we visited several times until we met mrs right at the RV show. ;)
Best of luck on your search and have fun doing it! If you feel like its a drag or frustrating you are doing something wrong. But I can't tell you exactly what... It's gonna be different for everyone..