Citysights DC, Washington

CitySights DC's signature double-decker bus tours of the United States's capital come which comes with hop-on, hop-off privileges—and there's plenty of reason to do both. Hopping on means informed narration in 11 languages, including Portuguese and German, and a break for tired feet. Hopping off is appealing too. It means leisurely exploration of some of the country's most important landmarks, such as the White House, Washington Monument, and Lincoln Memorial, whose beard grows if you stare at it long enough. Other tours cover similar terrain in different ways. On boat tours, passengers see the sites from the Potomac River, and on bike tours, they pedal themselves from locale to locale.