We have a membership in KM Resorts based in Wa. We also pay extra annual dues for access to affiliates C-C, RPI, Thousand Trails, Good Neighbors, and a couple more I think. Have not used the affiliates much so for.
Not sure what you want to consider in these? We've stayed in maybe 6-8 of the campgrounds so far and liked them all except for one. I guess it depends on what you want in an cg? They can range from being almost a gravel parking lot to lovely treed places with manicured lawns and well-kept throughout.
If you are planning to travel around a bit, you will find that these campgrounds can be far and few between in some areas or on some routes. For example, along the I-5 in Oregon, there's almost nothing to choose from and they won't be terribly exciting because not many go camping along the interstate. However, on the Oregon Coast, there's lots and lots.
Another thing is if you have the brochures with the campground descriptions in them, take what they say about them with a grain of salt. "Next to the ocean" can mean the water is 1/2 mile away and you can't see water. "Near great shopping and restaurants" could mean the cg is crap and they have nothing nice they can say about it. Sometimes a cg can be next to a train track, airport or industrial complex and it's NOISY... If you have a cg in mind, it's better to research them online in advance. Some of the best ones are small family owned cgs that are part of one of the large cg networks - stayed in one on the Oregon coast that is so nice that they even get repeat customers from Europe. However, a few can be not much better than a gravel parking lot. It's all about advance research.
We stayed in a small Good Sam cg this past summer and it was totally awesome. It was right on the waterfront (feet away) with fabulous views. The online reviews said it was one of the top few in Washington and they were right. The write-up in the brochure did not do the actual experience justice.
Stayed in a Thousand Trails in the summer and it was awesome. However, I got the TT wedged between trees on the way out and had to be rescued.
My fault though and another story.... Have seen a few other Thousand Trails and they have all been on the rustic side with lots of trees. Probably not all like that tho. I've read that some are pretty unhappy with T/T these days.
We are going to pare our affiliate cgs down to 1 or 2 or 3 for the next few years until we are both retired and ready for some extensive travelling. We have no issues with any of them (the orgs.). Doing advance research for a particular cg is the key. If more wilderness type camping is what you want, like say state parks or in national forests, many of the membership campgrounds won't thrill you. If you like full services, decent facilities, meeting lots of RV-ers from all over, personal safety, activities in the clubhouse, etc., C-C, RPI and all the others are great IMO.
A good thing about membership cgs is that because you have to pay a lot upfront, you won't get much noisy and obnoxious riff-raff like you can at public places like your KOAs and others. The only exception might be for cgs that rent cabins to anyone.
The most important thing about buying into a membership place is do as much online research as you can in advance before you go to a sales pitch. Everything is negotiable - the dollar amount and the features/benefits. You can be restricted to a state or only a few cgs. Then there's things like how far in advance you can book a site and how long you can stay in one stretch. Lots you should know about in advance. The time of day and day of the week can make a difference in how much you can squeeze them. If you think you aren't getting the best of deals, be prepared to get up and walk out. They can have a quota they want to meet and will bend more than you think. Or buy the minimum and try and negotiate upgrades later. Or, try finding a pre-owned membership, but be very careful about what's included in it. There's no such thing as a standard membership with standard features with a single price. It's an unregulated industry and you can be had if not careful. We were sitting next to a lady at the presentation we went to and she paid top dollar for every feature the sales guy asked for. Yikes.
DW is an accountant and she researched a membership place to death before going for the sales pitch. We had also won a "free" membership at an RV show. Wasn't really good for much but we were able to use it as a down payment towards the full cost and it was worthwhile. They often give away lots of "free" memberships at shows.
We are on track to have our membership fee paid off in under 3 years. After that, it's free camping at our KM Resorts campgrounds (9 of them in total). The daily cost at the affiliates can range from under a dollar per night to maybe around $30 or so. Depends on the particular cg. Definitely a huge savings in the long run and we couldn't be happier.
If you are in Cal., I've read that many cgs book up months in advance in the camping season. If you have a membership in a C-C or other org., they cannot turn you away. You may have to park in an overflow spot with no, or partial services, but you will always get in.
Hope this helps.
See you at a campground out there somewhere someday!