I don't know if Trailer Life is the same as GS and I think our TL is a few years old but we use it when we're on the road and find it easy to read. We also have the AAA camping guides for the areas we will be traveling to and through and we have a KOA guide too. The other guides we carry are individual State camping guides. Some times we get the AAA and the individual State guides before we leave home and sometimes on the road. I agree that the TL book could be split up by time zones and put four smaller guides in a package for a few bucks more than a single book.
If we are at home or in a campground with good WiFi, we also use the reviews from various sources and we use Google Earth for a look see. It has helped with picking locations by seeing what is in a CG and where it is.
Kind of a round about answer but that the sources we use.