See Western Europe on Just One Book!
Despite its obvious leaning toward budget travel, LP's Western Europe guidebook is all you need to find your way about the continent. It's tips on restaurants and sights to see is near-on faultless, and the bit nobody should miss: The preamble to each chapter includes all of the most important things like dangers and annoyances, and transport options to reach all your favourite sights. Best of all are the maps - if you only take one guidebook/map, then save some room for LP's Western Europe.