A knowledgeable guide can give a laser focus to any sightseeing visit, and this may never be so valuable as when you have very little time in one place. This is a very common occurrence in modern life -- hence the popular "36 hours in..." features in the New York Times every week. If you don't have a copy of the Times' recommendations, or you want to go off the beaten path they have cleared, the right guide can give you a customized and thrilling blitz through the destination of your choice.