Be careful of memberships. If the entry fee is below $100 and you are not contractually on the hook for annual fees you are probably OK. Anyway you cannot be out all that much if it turns out a bummer.
Frankly you may have some discounts already, if you are an AAA or AARP member. Some CGs will discount for cash. Ask. Negotiate weekly or monthly rates. If you are eligible for FamCamp you have the best deal going around.
KOAs may or may not be the most expensive CGs around. I have seen CGs over $150/night and they weren't KOAs. Yes, KOAs are tend to be noisy, they cater to families and car campers. If you like a bit of activity they are fine. Myself the quiet, 55+ parks, are not my cup of tea --- the sound of arteries hardening creeps me out. When we walk out dawg, we like to see people out and about doing things.
If one of you turns or has turned 62, get your self off to the nearest national park or monument and buy a Golden Age Passport. It gets you in free to National parks and sites, and 50% off federal camping fees. Best deal around.
Otherwise, relax. Most RV parks are whole lot less than motels or hotels in the area.