We have visited the Dom Rep four times. Two trips have been to a lovely little island, Cayo Levantado, with only one hotel, magical; excellent food etc, but no use to you as it is adults only.
The other two trips have been to the Bahia Principe el Portillo, (part of the same chain who run Cayo Lev), once with just DH, and last August with the full tribe of DSs and DGcs. It is on its own, not in a complex, with the most stunning beach, huge rooms, excellent food, fabulous for kids. We would happily have taken them there this sumner, but First Choice, the only UK operator who offers it, have changed airports and the transfer is now four hours not one. If you can cope with this, and we did it on our first visit, I am sure you would love the hotel, check out reviews and photos on Trip Advisor.
We have booked to take the kids to Mexico instead this August, but with the Grand Bahia Principe chain again, as we have found them to be absolutely excellent and reliable. It is in a big complex though so hoping for the best.
If you don't fancy the transfer to El Portillo, have a look at the Punta Cana area, but I think most hotels there are in a complex or form a continuous line along the, reputedly wonderful, beach. I'd tend to avoid the Puerto Plata end of the island.
We really loved the Dom Rep, plenty to do and see, very good value but be wary of suspiciously cheap hotels, or take industrial quantities of Immodium. We had no problems in this area.