Most of the hotels along and near the Malecón have casinos in them. Casinos in the Dominican Republic  are generally much smaller and have fewer games than the ones you find in the posh hotels of North America.
Some major ones in Santo Domingo  are the Hotel InterContinental (Av. George Washington 218, tel. 809/221-0000, www.intercontinental.com/santodomingo ), El Napolitano (Av. George Washington 101, tel. 809/687-1131), and Hotel Santo Domingo Casino (Av. Independencia, tel. 809/221-1511).
They are generally open 4 p.m.–4 a.m. You can play with Dominican pesos or U.S. dollars (preferred). The odds are generally similar to Las Vegas odds, meaning profits kept by the casinos and winnings that walk away with the gamblers are similar in Santo Domingo. Just like in Vegas, you’ll find blackjack, craps, and slot machines. You’ll find video poker, too, but often it is a Caribbean version of the kind you find in Vegas. Texas Hold ’em and Seven Card Stud are missing from the poker atmosphere and are replaced by a Caribbean version. Stay clear of Keno and Super Keno—the odds are horrendous.
While tipping the dealer may feel like a custom to you, it is not expected here as casinos have their dealers pool their tips to be evenly distributed among the other dealers (if at all). If you have questions, feel free to ask; most dealers speak English.