This will be our first time too! I'm travelling with my 8 year old grandson. Here is what we are doing: First day, we are going to Horseshoe Beach in the afternoon and in the evening we are going on the Bermuda Triangle night cruise. It's a glass bottom boat that turns on lights on the bottom of the boat so you can see the "nightlife". They have an 8pm and a 10pm time. On our second day, we are taking a Museum, Aquarium and Crystal Cave tour. These are all booked thru the ship and provide the transportation to and from except the return from Crystal Cave. We are going to get transfers ahead of time for a ferry ride back to ship. I know I've read that the bus transportation is good, but my first time at a new place, I like to know I have a ride back!!
If you can, rent a scooter and go on an adventure. We've been there twice and rented one each time. We had docked overnight so we just put our scooters just outside the ship at night. You are discouraged from renting scooters but we had no issues. We took off on one side of the island one day and did the other side the next. We stopped at secluded beaches, had tea at quaint tea houses and just had a blast.