Washington, D.C., might be the ultimate budget vacation spot. "Apart from your meals, you're probably not going to spend anything during the day," says Kate Gibbs, spokeswoman for Destination DC, a tourism organization. "Most of the great attractions -- the National Mall, the 19 Smithsonian Museums, the National Zoo and Capitol Hill -- are all free."

To stretch your travel dollar, look for one of the many hotels offering stay-two-nights-and-get-one-night-free deals, Gibbs says. Hotel rates also drop from December to February, the city's slowest tourist season, even though there is still plenty to do.

In December, the city has holiday decor, free concerts on the National Mall and ice skating. February is the monthlong "Date Nights DC" event where entertainment venues and restaurants offer special discounts, such as two-for-one tickets and dinners. The Cultural Alliance of Greater Washington also sells half-price tickets to local theater events year-round.

It's easy to save on transportation on this American vacation, Gibbs says. In addition to the Metro subway system, the city has the DC Circulator bus line that stops at most of the major sites and only costs $1 to ride.