I drove up to Bandy Creek CG this week (in the Big South Fork Nat Recreation Area, Tennessee-Kentucky) and bought my "lifetime" Senior Discount pass.. Not over joyed at being 62 years old.. but at least it has a few advantages. People feel sorry for you and let you buy stuff a little cheaper.
Anyway.. I don't camp in National Parks much at all.. but I do camp some at Bandy Creek.. This pass was only $10. It gives me a 50% discount on each night of camping. Sites at Bandy Creek are $22 per night.. So I booked two nights and only paid $22. They didn't charge tax either.. That's a pretty good deal. If I never use the pass again, I've already saved $12. And yes.. you can use the pass when you reserve online.. it's good at Nat Parks and Rec Areas anywhere in the U.S. There may be other things, besides campsites, that are discounted too... I haven't read all the details.
Do you buy or use any discount passes, etc for camping?