I think you have it about 75% right if your talking about "campgrounds" only. But you're going to be overlooking a lot. There are county campgrounds and there is a big difference between Natl PARKS and Natl forest campgrounds. You didn't mention Natl Forest campgrounds at all, many are great. And the size of you rv might keep you out of some places but not many if you have a long RV. Also many places have a City park, some are nice some are just a dirt field. Sometimes you have to get caught up in life an a private campground usually close to city and has washers/dryers, haircut and restock the frig. If the money bothers you (as it did us, until got our "old timers" pass) there is also BLM land, Boondocking etc. Many popular Natl Parks are like a mini city in prime tourist season.
More to your question
beginner advice on campground selection please
Read peoples blogs of where they stayed and how they liked the place. But here is also many other places to stay. For a change we like marinas and sometimes stay just where ever we end up for the night. Just what ever you like to do, with some common since and there are more places to stay than RV's. Just doesn't seem like that sometimes when your elbow to elbow at a park and the next night your all by yourself in the middle of nowhere. With a 6 month trip You'll find out the places you like and don't like.
