I agree with SJU and BGI suggested up-thread, as well as the Hilton in MBJ which is excellent for kids. Yours are just the right ages for the FREE kids club (at least it was free on my two stays). You can also snorkle and do a glass-bottomed boat ride. They have a restaurant at the golf course in case you get tired of the buffet.
One more suggestion, the Hilton in CUR. The property was a bit tired when I was there, but it has a small beach and a pool, and there are other things to do within easy reach.
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13F