I agree that Campclub seems to have more restrictions, but the number of restrictions at PA campgrounds is growing. It goes without saying, Dec. through Feb. or March are usually excluded in snowbird locations, but we see more and more PA campgrounds with a discount good only for weekdays or limited to only 1 or 2 nights. Of course, we usually only use PA for overnight stops anyway. When we are going to be in an area for a week or two, we are usually a little more selective.
The other thing we are finding with a lot of PA campgrounds is add-on fees. I don't know if Campclub is the same or not. The 50% discount is on the inexpensive base rate only; then they add $2 for water, $3 for electric, $5 for 50 amp, $3 for sewer, $2 to $3 for a pull-through, $2 for extra people or pets, etc. The fees for the extras are not discounted, so by the time you're done, instead of the expected 50% discount it's more like only 15 or 20%.