Ooh Ooh!!
I love this question, as I've been excited about it ever since I figured out who my three would be. It comes up often in conversations for me because I'm fascinated by who people pick and why.
My choices are based on people I feel I could have great discussions with and people I (hopefully) would be comfortable enough around to really enjoy the lunch.
1 - Walt Disney. For all the magical reasons we already know.
2 - JK Rowling. Sort of in the same boat as Mr. Disney, for me. Anyone who can so flawlessly produce an entirely new world for people to visit, whether literally like WDW or in their own minds, is a genius to me. Also, as an aspiring novelist myself, I would love to discuss the craft and her techniques.
3 - The Tag Fairy.
Juuuuuuuuuust kidding. I mean, no, I'd love to have lunch with the Tag Fairy, but I just...um...well, I wouldn't want to dream TOO big after all!!
Actually, my #3 is my DH. I consider this to be my loophole in the deal, cause, see...I'm not married. I'm not even in a relationship, nor do I have any suitable princely prospects. Imagine how exciting it would be to meet your Mr. Disney, JK Rowling, AND your true love all in one afternoon!!
Of course...imagine how awful it would be for me to show up for lunch and see an empty chair at the table....
(PS - Reading all of these makes me extra grateful that I can still spend time with my own grandmother, so thanks for that.
In response to other people:
Britney Spears: I've actually met her several times (sat next to her at the MTV VMAs a couple years ago) and she's really very sweet. Somewhat of an idiot, yes, but sweet nonetheless.
Johnny Depp: He used to be my #3 (until I got clever...he he). From what I've read and seen of him, he's not only immensely entertaining and otherwordly handsome, but he's intelligent as well. He'd definitely keep the conversation alive, and I think Mr. Disney would LOVE to meet Captain Jack Sparrow!!
)
DONNY OSMOND 
).....P
