National Geographic's Guide to the National Parks of the United States (3rd Edition)
It's impressive how much National Geographic can squeeze into a small book. Each entry tells  how big the park is, describes its flavor, indicates when it's best to go and how to get there, and includes an  elegantly useful map. A detailed tour of the sights includes glorious pictures (450 total), highlighting the  best of each park. But practicalities are not neglected: entries include headquarters' addresses and phones,  entrance fees, facilities for the disabled, accommodations, pet regulations, and what there is to do. And so it  goes for each of the 54 parks--it's a gem of a guide.