Hidden mickey idea is great. Also try the new/rehabbed rides since you were last there. What about the castle walk through?
Try to get your photopass picture taken as many times as you can and then build a photobook based on those.
Eat your way to Unique DL treats... Tigger Tails, Hunny pot apples, Monte Cristo Sandwich, Mint Julips (Any more???)
If you have those who are young at heart... got to BBB or Studio 365 and have a make over.
Go to DTD at night and listen to all the great street music.
See Aladdin before it goes away..
If you are staying at DLH get their activity sheet each morning and take their tours or quizes (open to the whole family)... The quizzes made riding the jungle cruise and Pirates more interesting for DD.
(Do they do this at other DLR hotels?)