I don't have a daughter, but I am a daughter...I just booked a Family Scavenger Hunt Experience in the Magic Kingdom for my family which sounded neat to me. You could also go shopping, let her make every single decision about the whole day, or take time to do some of things you might not have in the past, like Sorcerers in the Magic Kingdom or the Phineas and Ferb quests in Epcot.
I let my five year old plan an entire day once and it was great fun. It was totally different than the day I would have planned for him. We didn't even enter a park, spent hours at the
Lego store, and went swimming at night in 60 degree temps. Oh and ice cream for breakfast!