It sounds like you have a lot of wonderful extras in there already! We've done everything you listed & you made some great choices. Did you ever consider "Dining with an Imagineer?" It really is a neat experience in a nice dining environment & definately best for adults.
To answer your question, the ONE thing I wish DH & I could do in WDW that we've never done.... Hmm, that would be sleep in Cinderella's Castle!
I know you have no control over that but wouldn't it be wonderful if you won!?!? Much pixie dust!