A digressive, philosophical riff on desire, happiness and the experience of travel by the author of "How Proust Can Change Your Life." What is the point, after all, of traveling? Read this book, in part a manual of how best to experience a place, and find out. In five sections, arranged by category: Departure, Motives, Landscape, Art and Return. De Botton, a philosopher, enlists painters, writers and other historical figues as guides in each essay, covering wide-ranging topics from airports, landscapes and museums, to holiday romances and shopping.  (TVL13, $13.95)