I was on the Majesty back in October of 2007 for my first cruise. I assume your ports of call will be Nassau, CocoCay, and Key West. In Nassau, take a cab over to Atlantis. It should be $4 USD one way. Don't bother exchanging your money, as when I was there, $1 US = $1 Bahamas Dollar, and both are widely accepted.
I don't know what you like to do, so it's hard to say what to recommend. I did snorkeling in CocoCay, which is RCI's private island. Because of this, you should be the only ship there. However, this is a port where you have to anchor in the harbor, then tender ashore, so allow time for that. There is a barbecue style lunch at this port. Here, I did snorkeling and parasailing, both booked through the ship.
Not too familiar with Key West, so I can't give you much help there. Again, I did the parasailing excursion as well as a glass bottom boat tour, both booked through the ship.
Enjoy your cruise! As kls stated, this is a great ship for a first cruise, if this is your first.
2007 - Majesty of the Seas (Bahamas)
2009 - Enchantment of the Seas (Western Caribbean)
2010 - Freedom of the Seas (Western Caribbean)
2013 - Golden Princess (Alaska, roundtrip from Seattle)