Travel with Children
TCI is a fantastic place to take kids. Although you may struggle to find specific programs and activities for youngsters outside major resorts, that's not such a problem when you consider the beaches, reefs, water sports and general freedom they'll enjoy. And all-inclusive megaresorts such as Beaches have so many diversions and activities for kids that the trick will be getting them to leave.
Kids not yet old enough to dive will be able to snorkel at reduced rates with outfits such as Big Blue; those too young (or too timid) even for that can still come face-to-face with reef life, riding the Undersea Explorer.
One difficulty for those with infants in strollers is the scarcity of sidewalks. Beyond Grace Bay, Turtle Cove and similarly tourist-rich areas of Provo, sidewalks don't exist, and you can be forced to walk on the shoulder of the road. The saving grace here is that, Provo excepted, traffic is negligible throughout the islands.
Dedicated changing facilities won't be found outside modern resorts and one or two restaurants and transport hubs. Prepare to improvise.
Overall, any difficulties you meet will be outweighed by the pleasures of taking kids to a warm, relaxed, beach-bedizened place where children are welcome everywhere (except perhaps the swankiest 'adult' restaurants).