Passport America Life Member - we stay at PPA parks about two or three times a year.
1) I never go to a PPA park for an extended stay. They are for a couple nights when getting from place to place. I never plan my trips based on PPA parks, but if I have a leg where I'm only going to stop a night or two - PPA gets a look.
2) Always check the rules and rates, call ahead and make sure the park still takes PPA.
3) As mentioned above - two or three nights pays for a year membership.
Some places we've used PPA at half-price rates. Lake City, FL; Daytona, FL; Hurricane Mills, TN; Cape Hatteras, NC; Sunset, TX; Texarkana, TX.