IMHO I would not put out money for a membership to any of the RV membership clubs. Too much can change over time as you saw 'luckily' first hand before you forked over all that money! Over the past few years I have heard horror stories about RV CG clubs, leases, and seasonal CG's going financially bust and putting campers and their RV's in precarious situations.
When I started out I bought all the memberships. As of 4 years ago,I belong to none. Found out you don't need them and none of them served me as they had professed in their brochures.
There are 'plenty' of simply high end resorts all over the US that look, serve and work like a private club CG. No prepaid membership needed!
I've stayed at many of them and have to admit after a few months of staying at the generic CG's sometimes they are a welcome experience to decompress.
Personally I would rather do that and be able to change travel plans any time I wanted and not feel like I'm paying for something I am not using 100% of the time.