If you call the front desk of your resort and tell them you would like to have a birthday cake and balloons in the room when you check in they will arrange it for you. I think I would get a special birthday present and see if they can sneak it into the room for you. You didn't say if your 16 YO is a girl or a boy but if it is a girl you could get some type of Disney charm to remember the trip by. They have a nice selection of Disney jewlery at the market place in the World of Mickey. (I think that is the name. Have a great trip and enjoy the holidays.