We choose as our first choice, national parks, national forests, state parks, Corps of Engineers, county parks and even city parks. We love natural surroundings and avoid private parks as much as possible.
We have a 40' motorhome and don't find a problem fitting into these kinds of parks but you have to do your homework. You can find some kind of hookups in all of these types. Not every one of the national parks, etc. but certainly in some of them. Perhaps not full hookups but even national parks or forests will offer electric sites, sometimes water and most often dump stations. All work for us! Also, we don't require any hookups if that's where we want to be. All RVs are self-contained so really, why do you need hookups? You just learn to conserve. It's very doable.