Hi Singer!
How old is your child? I would highly recommend the horseback riding on the beach if he or she is old enough. Gypsy Ranch has lovely horses and is located between here and Cabarete.
Speaking of which... you must spend at least one day in Cabarete... dinner on the beach, under the stars and palms, surf pounding in, is magnificent.
There's a fun go-kart track near Puerto Plata and a water slide just west of Sosua.
Also, I highly recommend Rocky's... for the food, music, and people-- if you spend a little time there you'll stumble into several DR1ers who will be delighted to offer suggestions. Many drop by in the morning for a good Western style breakfast, so don't be shy... just ask.
Actually, if you let people know ahead of time when you arrive, there'll definitely be a few happy to meet up with you to sit and discuss your preferences.
And, finally, if it happens that you're in town by July 3rd, even better. We're getting together on the Sat eve, so you can meet a couple dozen in one swoop.
Have a great trip, and hope to say 'hi' in Sosua.