Quick response. Not Dominican, but I live in Atlanta and have several Dominican friends around here. We've done our share of partying.
There used to be a pretty crazy Dominican/Latin Sunday night at a restaurant called Santo Domingo on Jimmy Carter Blvd and Britt Road. That died because it got too popular and had issues with both violence (fights) and underage patrons. Still a decent restaurant, if you want Dominican fare. Reasonably priced as well.
La Rumba on Roswell Road (OTP) has its moments on Friday nights. Just gotta know when those parties are being promoted.
While I haven't been in a couple of years, Havana Club in Buckhead had a decent scene. Music covered all types, including bachata, reggaeton, salsa, merengue, even vallenatos. Just depends on who's djing. I've also been there when they had live bands. Can be a bit pricey, but nice spot if on a date to cut loose.
Tongue and Groove used to have a Latin night mid-week. Again, I've been out of the club scene for a while now. It was decent and even had salsa lessons. Plenty of reggaeton, merengue, salsa, etc....
There's others around. When I think of them, I'll post it.