We've celebrated DD bday many times @ WDW. We've done:
- the WISHES birthday cruise,which was by far the best!!! They decorated the boat with balloons and had a cake/drinks onboard for her. People from other boats in the area were yelling "Happy Birthday" to her- very Magical!!!!
- got a birthday badge at Guest Relations in the Park we were visiting. I actually picked it up the day B4 and surprised her with it the morning of her bday. The CMs at the bus and hotel guests @ Bfast noticed it and all gave her birthday wishes prior to getting to the park. CMs will definitely notice it. Once, a CM announced it over the loudspeaker on TT, and she just about beamed for the rest of the day!
- when making ADRs for the day, I had them note that it was DD bday. We've had cupcakes, confetti, certificates @ different restaurants.
- ordered a basket from Gifts of Lifetime filled with goodies we could all enjoy
- had ADR @ 1900 PF once, and Prince Charming presented her with a cupcake and sang Happy Birthday to her! Another year, we ordered "Cindy's slipper" for her as a surprise dessert!
Your princess will enjoy celebrating her Birthday @ Disney! Good Luck in whatever you decide!