There is no plot to “The Travel Book: A Journey Through Every Country in the World” (Lonely Planet, 448 pages, $50), but the underlying theme is simple: (OK, really pretty pictures.) But what the text lacks in depth, it make up for in savvy, authoritative suggestions for the best things to see and do, as well as the “Getting under the skin” category with quick picks for how to experience the culture, even before going there. At a time when most U.S.