Do you feel that there is plenty of activities there besides Beaches to keep a 10 year old busy during spring break.

Might want to post this on the Caribbean forum.
TCI is verrry quiet, but if your child loves the beach/pool, he/she will be just fine there.
If you want playmates, Beaches on Provo always seems to have lots of kids. (Since you capitalized "Beaches," that may be where you are planning to go.)
My guess (we have no kids) would be that they have all kinds of activities to keep "Jr." busy...

Sounds like you are having trouble deciding between the Carribean and Hawaii.

Exactly. any suggestions
We are Grandparents and don't want to do the Disney thing...(Young grandparents)

Hawk's Cay in the middle Keys has a great kid's program. Another thought is Key West. Snorkeling, bicycling, treasure museum, walking tour of haunted houses, day trip to Ft. Jefferson, Key West Aquarium.