We looked for Good Sam camping discounts but out west we probably only used it about 1/3 of the time. Mostly at the full service RV parks.
The Flying J gas discount did not have many stations off the Interstate so we used it very little.
The biggest features for us include their list of campgrounds, the discount at Camping World and I like the four Trailer Life mags.
If you have an idea of where you want to go, checking out the Passport and Sam's opportunities before hand would be a good idea.
Good Sams also like to send RV insurance info.