I use RVPARKREVIEWS.COM to pick my campsites.
- Pick the state, then the city and it will show campgrounds with reviews added by your fellow campers. Works great.
Join Good Sam - just about every campground gives you 10% off if you have their card.
Consider joining Passport America. You can get 50% off, but there are restrictions. I have always saved way more then the membership cost though. You can sign up at your local CW. They usually have the PPA directories so you can browse locations and see how it can work for you.
There are soft cover books available for Corps of Engineers campgrounds as well as state park campgrounds - Google and Amazon are your friends here.
Get "The Next Exit" soft cover book. Shows what's located at every exit of every interstate highway in every state. Terrific. There's also an online version but I like the book better.
I also have the gas buddy phone app. Same type of format, except it keys in automatically on your location, then brings up all the surrounding gas/diesel stations with prices of fuel.
Take a good RV GPS with a 7 inch screen and also an up to date atlas.
Tim