In a nutshell, hotels use Priceline.com to sell excess room inventory at prices that are usually at least 30% off the already-discounted rates you'll find at sites like Travelocity and Hotels.com.

Foreign exchange fees on transactions made outside the U.S. are 3% on most credit cards. Needless to say, that adds up fast when traveling in foreign countries. So a commonly asked question is “Which credit card can I use when I’m traveling abroad to minimize the foreign exchange fees?”

Travel expenses that qualify for the 3% reward include airlines, hotels, trains, car rentals, cruise lines, cabs/limos, buses, travel agents, and timeshares.

It's also noteworthy that Capital One is one of the few credit card issuers that totally eliminates the 3% foreign exchange fee on transactions in foreign countries. So if you use your credit card while traveling abroad, Capital One will save you yet another 3%!