Some suggestions
Here are some resorts I've stayed at and recommend:
Sunscape the Beach - this is my favourite: beautiful, oceanfront, great food/restaurants, huge pool that runs the length of the resort grounds - stayed here a few times
Grand Flamenco - liked it but didn't love it, the disco Mangu is right there though and it's a good place to party
Ocean Blue - really like this place, no complaints
Iberostar Dominicana - really liked this place too and no complaints on this one either
Enjoy your vacation!