What does she like to do? Is she happiest at the beach? Does she like to windsurf? Ride horses? Mountain bike? Hike? Golf? Tubing or river rafting? The DR offers so much. As long as you don't go to a hotel in a big complex, like Playa Dorada, she will have exposure to local culture and hear plenty of Spanish. But what sorts of things does she most enjoy doing? If you give us an idea of the activities she would most like to engage in during the family vacation, we can be of more help in suggesting a location.
All inclusives have their place, but she will get more exposure to the local culture if you go to a non-AI.