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The Freedom Of The Seas is a great ship. It certainly has lots of things to do while aboard. This was the first ship to have a Flowrider.
October weather is typically pleasant with temperatures in the 75-85 degree range. A passing shower is common on any given day just like any other tropical area. But it rarely lasts long.
Coco Cay is a nice little private island. They have built it up over the years and there are several little huts with bars, souvenirs, and the buffet lunch. This is a beach day on your very own 120 acre island. It is a tender port (you anchor and take small boats in to the island).
What to do on the other two stops depends on what you like to do, or perhaps try something new. If you look at the tours offered for St. Thomas and St. Maarten on the Royal Caribbean website you'll get an idea.
The ship is a destination in itself. If this is your first cruise you will be bowled over by the Freedom Of The Seas.