If you are in the north of Broward, I'd definitely recommend Sugar Sand Park in Boca Raton. Both of my boys have loved it for as long as they've been able to walk. There are hands-on science exhibits an explorium, cultural bits, a skate park etc, but the jewels are the Merry Go Round ($1/ride, but adults are free while the kids are little) and the science-themed playground, which is safe and fun for kids of pretty much any age and simply spectacular... definitely worth checking out even if you don't live in the north of broward if you've something else to do up north, since it's not far off of '95 (on the north side of Military trail between Hillsborough and Palmetto Park Rd).
It's best to always make sure that you have a spare set of clothes handy, since there *are* water play features and no matter how hard you try, there's not any guarantee that they won't be able to get themselves soaked in pretty short order.
-Scott (S.'s Husband)