Sorry to say but you’re out of luck, if you came to Santo Domingo looking for erotic massage. You might get a handjob at one of the salons around Zona Colonial, but don’t count on full service. Spa Odisea (http://spaodisea.com/) at Coplan Plaza, Autopista 30 de Mayo is a decent pick.
A sensual massage with a happy ending should cost you around $50 in Santo Domingo. Honestly, I would recommend an escort agency that could provide you with girls with massage skills instead.