Wondering if GRVE is the outfit that I investigated and discounted after being bombarded with E-mail messages. If it is, I really do not like their method of advertising. Evidently it does not work, cause I do not remember them.
Good Sam is a standard and will pay back in discounts at camping world. Toilet paper and propane is a reasonable price even if that is all you buy there. The 10% kind of takes the edge off of high park prices. AAA often is available as an alternative. The winners are the parks that discount for GS and cash as well. Not many of those, but they are out there and worth asking.
The KOA program is a must if you use their parks. It helps get the price down to where it likely should be from a value perspective. If you use their facilities a lot, the rewards program helps too. We find that KOA is a good default when all the park prices are high or when they are the only game in the area. Yes, we travel without reservations and have to punt from time to time. We are not upset with the park quality, get a bit of a discount with the membership, build on the rewards bank, and if we take a site with electrical and water only the cost is not so bad. You just have to dump on the way out.
PA = 10X good. Go for it!
Safe travels. Pat