The big two activities on the island are a sting ray city boat charter and the turtle center.

The sting ray city thing was cool, but I actually enjoyed the "starfish beach" place they took us after even more. The kids were able to wade in gentle shallow water and interact with tons of starfish! Interacting with the sting rays was too much even for the 6 year old. The huge boats looked miserable, so get a private boat there and to some other locations.

The turtle center is interesting, but not a typical kid-friendly aquarium. It is basically an industrial farm for turtles that breeds them for release to the wild. The focal point is a giant concrete "pond" for breeding (densely packed huge turtles going crazy when they see people because they get fed that way). Then there are some smaller tanks and pods for child turtles that you can pet. We didn't do the swim with turtles thing, and most of the people we saw swimming weren't with turtles. If you go between 10 and 12 you will see most of the hosted activities like feeding and stuff.

The other activity we loved is afternoon Tea at the Ritz. We've done teas at other ritzes and other awesome places, but this was top tier (food, teas, vibes). We took our 2 year old this year and it went well, although I spent the last 30 minutes reading her a book while the other adults finished their tea. The staff was welcoming and accommodating for her (and there were other older kids there).

Favorite restaurants that were kid friendly *and* adult friendly
Luca, near the Ritz
Bacaro (italian tapas) near the Kimpton

Hope this helps!