This is a harder question than it seems. I, like most of the people at the cruise lines, am having a hard time coming up with something original unless I name it after my wife. I'm not sure the "Betty B" would go over for a cruise ship. It works my boat but not a cruise ship.
We could go the way of the Kentucky Derby winner and name the ship: "I'll Have Another." It works for cruising.
Take care,
Mike