As others have noted, renting for a weekend or a few days is a good idea to get a feel for what kind of space you need, how you exist "cooped up" together in close quarters, and so on. I have only two points to add - #1, don't be afraid of a large class A because of its size - they are really fairly simple to drive, and a few hours of practice will show you that. A 40' Class A is FAR easier than a 15' pickup and a 30' trailer to maneuver around. The B/C class units, on van chassis', can sometimes be tricky, because some people will drive them like they're not much more than big cars, and that's a mistake. With an "A", you don't ever fall back into that nonchalant attitude. #2, iRV2 and other net forums are useful mines of information and help, but don't let the NEGATIVE posts about things color your perception - you might read a post here and there that "xyz" is a crappy coach or "I've had so many problems with my ABC" or what not - but you have to remember that generally, people don't come on internet forums to say how great their experience was, or how trouble-free everything was. The small percentage of negative experiences, as in all life, get the most press, but are not typical. For example, RV fires - you see the horrifying skeleton of a $300,000 DP by the side of an interstate, and people chime in about their near-tragedies, but you never hear about the hundreds of thousands of perfectly safe, happy, trouble-free RV trips that get taken by all kinds of people all over the country. Like plane crashes, they don't make the news.
So have fun, look around, and don't get too overwhelmed by which brand is best or which type of RV is 'best' - decide on a floorplan and space layout that you like, that fits in your budget, and that gives you the most pleasure - some people are just fine with a popup travel trailer behind a Chevy Silverado - others need a 45' diesel pusher that costs three quarters of a million dollars.
Always remember, you're a unique individual - just like the other 7 billion people on the planet...