We were at those ports, plus Key West, while sailing the Majesty of the Seas in June, 2001, with our family which at that time included a 19 year old son and a 9 year old daughter.
The Stingray excursion was the highlight of the cruise for the whole family. A must do!
At CocoCay, you tender ashore. There's lots of beach chairs, and they sell you great drinks in CocoCay mugs, that we still have and use. I laid on the beach chair most of the day. The daughter played in the shallow water nearby, picking up shells. The son and husband went snorkeling for a long time, and also did the WaveRunner excursion. They said it was great! Lunch was under a tent, kind of picnic type food, but it was great for a private island!