Here ya go. Pick one of these four and you won't go wrong.
www.hawkscay.com/ Real nice, a pool and a natural pool. For the kids, there are dolphins in their own pool.
www.keylargoresort.com/ On the bay side, nice kiddy pool next to the adult pool. Close to John Pennicamp state park.
www.littlepalmisland.com/ Never been there, I hear it's the nicest place (and most expensive) in the keys.
www.cheeca.rockresorts.com/ Super nice Rock resort. A bit on the pricey side, right on the ocean.