When purchasing an atlas, there are a few simple things to consider to ensure you're getting what you need.
The Gazetteer: The extensiveness of this geographic index will potentially allow for more detailed research in the book.
The General Map Description: Your personal readability of the cartography will make the atlas more enjoyable. If you have a preference for physical or political maps, or an interest in satellite imagery, give this section special attention.
Images and Maps: This description will tell you the number of maps, and the number of any satellite or photo images.
Inset or City Maps: Some atlases show major metropolitan areas with street detail. Some also include geophysical regions, ports, and islands.