We're owners (of a 3 bedroom, private pool villa) at the Westin St John. We bought before we had our daughter, now 5. She's been going every year since she was six months old. The Westin is extremely child friendly - there's a kid's area (maybe six inches deep) in the main pool, there's a playground, and if the child is over 3 and potty trained, there's a wonderful kid's club. The entire island is a paradise; granted the Westin's beach isn't the best on the island, but it's better than any beach I've seen in the states. The island has 39 beaches, and most rarely have more than 20 people on them. Alot depends on the time of year you go, but there's a great discussion board on VINOW.com where you could get much more information. Feel free to email me if you want more info.
Lori