It all depends on where you travel. If you go where the clubs parks are anyway, you can save $$ via a membership. But if they aren't where you want to go, i'ts a waste. You can save a lot via Passport America, Camp Club, Freedom Resorts, etc. discount clubs as well, and you get a much wider selection. Each of those groups have 1000+ choices and the cost is much less - around $35-40 per year.
We bought a 1000 Trails membership in 2008, after avoiding any such commitment for years and years. Got great value one year, but health issues kept us from traveling to any of their parks the following year, so we paid for nothing in 2009. One year of missed opportunity like that can wipe out a lot of cost savings.
2004 American Tradition; 2014 Buick LaCRosse
Homebase in the Ocala Nat'l Forest near Ocala, FL