We like to stay in public campground, so traditional campground directories don't cater to the places we like.
We use "Don Wright's Free and Cheap Campgrounds' and "Camping with the Corps of Engineers" from FREE Campgrounds -- West
Online we use Fred & Suzi Dow's website Campground Directory and National Forest Campgrounds
and RV Park Reviews :: Home
. I also bookmark state park websites and use places like Free Campsites, Free Campgrounds and Boondocking Locations
who has many cheap pay places listed.
We also use the phone book.. which is how we found the campground/Rv park we're in right now.
I will pick up a Woodall's and hang onto it for a few years (just threw away my last one... I don't think I will replace it). We have a test... We look up Westminster Sc to see if they list Chau Ram State Park (tiny state park w/ campground). They haven't in years. If they leave that out, what else do they leave out. Also we like to look up descriptions & rating of campgrounds we know. Woodall's, TrailerLife have ratings and descriptions that we find questionable.
The internet is more up-to-date and I can get more info (usually) from websites.