There are Christmas concerts at the Santo Domingo cathedral - probably on Christmas Eve, but double-check nearer the time - DR1 News usually announces the exact date and time in the run-up to Christmas, and the Reyes Magos (Three Kings) procession through the Colonial Zone, usually on the 5th January.
Santo Domingo's Malecon is usually the site for a huge New Year's eve party with performances by Dominican music stars. Expect lots of fireworks most of the night, every night, and not just on New Year's Eve.
