Food: for one thing, didn't expect that the Indian and Japanese food in the Windjammer/Jade would be so excellent, nor that the food there would be better than in the dining room.
Entertainment: esp. the ballroom dancing lessons, the NASA lecturer, the shows, would be so awesome.
The Promenade area: I don't think we'll ever like a ship that doesn't have that central meeting area with the entertainment, shopping and Promenade Cafe.