You can grab a taxi and go over to the casino for $4.00 PP, plus I think $1.00 for the toll to get over the bridge. You can also get a water taxi for $4.00 PP.
The $47.00 must include the tour of the grounds and maybe to use the beach.
All you do when you get off the ship is take a small walk into town and grab a cab.
The Atlantis is my husbnads most favorite spot on earth! He loves casinos and he says its the best! Have a great time!