Old San Juan, Puerto Rico

I consider PR to be a great “bang for your buck” destination. Not only can you find a reasonably-priced flight, but there’s less planning needed if you’re traveling from the continental U.S.; you don’t need to bring a passport or exchange currency, and most locals (at least around San Juan and other touristy areas) speak English as well as Spanish. At the same time, you get a true cross-cultural experience and there seem to be endless places on the island to explore.