The Sierra Club has always had a major publishing program, with landmark books such as "This is the American Earth" by Nancy Newhall and Ansel Adams. John Muir observed that you couldn't rouse people to help save a place they had never seen, and started the Sierra Club outings program. These guidebooks carry on the tradition, helping people find the great places, and understand their value.
I have found several of these guides to be very helpful. In particular, Adventuring in the California Desert, and Adventuring in British Columbia led me to some amazing places I might not otherwise have known about.