If you can, try to hire a camper in your area. That will give you a good idea of features you love and hate. For example, when we hired a soft floor we discovered that needing to pull out the gas bottle to connect to the kitchen was a major nuisance, but that hard floors don't really have a lot of storage space.
Oh, and check out the caravan and camping shows in your area. Also, the sneaky thing is to visit your local caravan park and offer free beer to anyone with the kind of rig you might be interested in. After a few beers they will tell you what they hate...