Gambling in Puerto Rico has a different flavor from many other destinations on this list, mostly because of the setting: The casinos are surrounded by Caribbean beaches, rainforests and eco-adventure opportunities that might make those free mid-day martinis at the blackjack table seem like a somewhat-less-great idea. Zip-lining is not for the drunk.
The island has more than 20 casinos, with entertainment and restaurants and hotel rooms on site, in a mix of Vegas-style complexes and ones with a bit more local flavor [source: SPR]. Salsa clubs, rum drinks and an overall Caribbean vibe are everywhere, lest you forget where you are. Gamblers with downtime can also experience 270 miles of beaches (of the white sand, gold sand, black sand and seaglass varieties), kayak trips to a bioluminescent bay and handmade mojitos by the sea all hours of the day or night [source: SPR].
Check out some other local flavor beyond the city zone while you're there -- coffee plantations, Old San Juan and art festivals make excellent day trips. The island is tiny, so you can do more than one thing in a day and still make it back for some late-night table games.