I actually think that the scrapbook is an AWESOME idea!!!!!! Very creative.
I think if it were me, I'd do like a vacation time line, first trip to the most recent, then maybe for the page telling your mom about the trip you have planned for her, I'd maybe do like a pocket, or something like that, that would hold your actual plan tickets, or your tickets of some sorts.
OOOOOOOOOOH!!!!!!!!!!!!!!!!! Have you seen those Disney commercials where the people find the invitations where they're least expecting it? Like the one kid finds it in his desk at school, I think a person finds it in a menu? It's the invitations to spend a day on your birthday or what ever. I would totally try to make that invitation!
Or do you have a Micky Mouse shaped balloon? You could do something like this:
You could add just an ordinary photo of your favorite spot in Disney, and then add the words "Vacation 2009" to the last page of your scrapbook; when your mom turns and looks at you funny, you could pull out that balloon with the invitation attached, or the plane tickets or whatever.
OMG ... What a great idea!!
You and your mom both are so lucky to have eachother! I cant wait to hear out it turns out.