In NJ I went to the beach all summer. I did all kinds of free stuff, but if I was in the mood, I went on the boardwalk, played games, arcades, and/or went to the amusement park on the pier.
CocoCay is just that. It is a beach day, but if you want something else, than you can pay for it. It is not a theme park. It is an area, with options for a family or yourself, but yet you can still just go to the beach.
I personally like the giant pool, with a swim up bar. I like the vibe of the place. I don't use the water slides or the activites. I don't even spend money. It's just a nice day, and I prefer it over Labadee.