Ahoy, Michelle!
One of the best part of a Disney Cruise is that you can always be celebrating, and it doesn't cost you anything! If you head to the Guest Services desk, they can give you a "Happy Birthday" button for your son. If you note the celebration on your reservation, you might be surprised at dinner by your servers with a birthday cupcake or special dessert, as well as a choral collaboration of "Happy Birthday" by your servers and some of the nearby servers as well.
If you would like your stateroom to be decorated upon arrival, you can order the Birthday Celebration Package in the
Gifts and Amenities section on the Disney Cruise Line website. For around $52, you will get a birthday banner in the room, a Disney Cruise Line bed runner, a birthday card, and a large Happy Birthday magnet on your door. This will all be in your stateroom when you get there on your embarkation day.
You can also order a celebration cake, if you wish. These are available to be ordered in the Gifts and Amenities section as well.
I hope this helps with your cruise planning, and you are able to make your son's sixth birthday completely DREAMy!
Happy Cruising, Tracy V.