My folks had joined several of the membership networks when they were full timing. Periodically, these things would go bust, and change all the rules/benefits. Not surprisingly, you'd still have to keep paying. They can bankrupt, but you can't break your contract.
I'd rather pay as a daily/transient and choose the best places to stay. Some of these so-called private parks will take people off the street as dailies. Each seems to make it's own rules, so you never know.
Good Sam is a good deal - I also buy the roadside assistance coverage. You best money spent is to buy a campground guide - they are several - and look for interesting places to try out. Certainly I'd camp for a couple years before I bought into something.
From what my folks experienced, these memberships cater to the "get something for nothing" crowd (present company excluded, of course!
). I think they take advantage of them and they are often left disappointed, because there really is no free lunch.