Good Sam gets you 10% at a lot of RV parks, and discounts at Camping World. But you can generally beat Camping World's prices on-line (amazon.com comes to mind). We find the convenience of Camping World very handy, especially when we're on the move and not necessarily stationary enough to receive shipments. So we use it, and take that 10% when we can.
FMCA is not only a great group of people, but the member benefits are really good - especially their Michelin tire program. FMCA also has discounts at a lot of RV resorts not discounted otherwise, but they tend to be higher end, higher priced parks, so the savings are somewhat an illusion (unless you tend to frequent high-price parks).
In addition to 1000 Trails and Passport America, we also have RPI and ROD, both of which save us money on RV parks most years. We also have Good Sam, FMCA, and Escapees memberships, all of which tend to pay for themselves most years, if not in actual dollars in the conveniences they offer. The FMCA and Escapees magazines are pretty much the best out there, and the Escapee-owned and affiliated RV parks are really good values if you want to go where they are.
No real need to join anything until you think you might get some benefit from it. They all make it easy to give them money. If you're thinking about 1000 Trails, be sure to check the resale market. You'll save a bundle if you can get a membership package with the features you want and/or will use.
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