I would go to Santo Domingo and stay in the Colonial Zone at the Hotel Conde de Penabla. The hotel is reasonably priced and has a great outdoor cafe directly across the square from the oldest church in the new world. The Hard Rock Cafe and other bars and restaurants are all in walking distance and there are many historical sites to see. Stay there for a couple of days and then move to the malecon, Mariott Renaissance Jaraguas Hotel. They have a nice casino attached and a beautiful pool area. There is also good night life in the area. This hotel is about a 10 minute taxi ride from the colonial zone. Good luck.
LTSTeve