[B_and_D]

There may be some state specific books, where do you want to camp? I have the Tom Stienstra books for both WA/OR and CA and find them very helpful (at least the CA book, haven't had a chance to get to WA/OR for an extended trip yet).

Edited to add:

He's more of an outdoorsy guy than an RV'er, but the listings do tell you what amenities the campgrounds have.