We had to catch a bus to go and come back, and it took about 20 mins to get there, Atlantis is cool for the kids but nothing special for adults, just a hotel with water slides. My kids would have liked to do the dolphin encounter but it was too late when we tried to book it.
The mini boats were great and the snorkeling was fine. What was horrible was that when we met the lady at the port we waited for an hour extra first because she didn't know how many other people might be coming and then because our pick up taxi was busy getting people somewhere else. Then the ride to the place where the miniboats were was like 30 minutes.
The Segway tour in St. Maarten is great and it is right at the beach close by the ship, which is called Grand Bay Beach. You can go to the beach and just relax there and some can go on the Segways if they want.