We too are members at Travel Resorts, and mostly use the Gettysburg location. We would say if you camp a lot then buying a membership would be a good idea, but you really have to think if it is a good deal for you or not. Last year we camped just in Gettysburg around 55 nights, so it was well worth our dues and maintance fees last year.
We also have coast to coast deluxe, and we find this to be the best if you are going to travel. For us we have to stay somewhat close to home this year.
I know this is a little off subject but Gettysburg resort is getting harder and harder to get reservations for the good sites. I think they are overselling their memberships. If I had it all to do over again, we would NOT have bought a memberships but would rather only buy Coast to Coast and camp for cheep prices. Just my 2 cents.