I'll second what most everybody else says about checking out some RV shows. That's probably the best way to get a general feel for what is available and what the relative pros and cons are of the various types of RVs.
If you'll be moving around frequently, give a little thought as well to a class C or class A motorhome. Setup and tear down is generally faster for them than for any sort of trailer (less stuff to hook up), and there are some advantages to having your home already there while traveling—it's a lot easier to grab a cold drink from the fridge or make a quick potty stop when you don't have to get out and walk around and fumble with keys, etc. There are also disadvantages, of course.
I would suggest looking for a good used unit when actually buying. RVs depreciate in value quite quickly, often far more quickly than they wear out in the first several years.