Having never been to St. Kitt's, I can't comment (although perhaps we'll try there next year), but we took our boys to the Cancun CasaMagna last year and we were all treated very well. It's RIGHT NEXT to the JW, so we'd spend 1/2 day by the Casa Magna pool/beach, and then walk the 50 yards and spend the afternoon by the JW pool (it's a bit nicer and more interesting for our little ones).

We're going back to the Cancun CM this summer again, we enjoyed it so much, and I understand that both properties have had major refurbishments as a result of the storm.