Hi there, Tara!
I'm just giddy with excitement for your family! What a super special vacation this is going to be for you guys!
I have to tell you, surprises are my absolute favorite thing in the whole world, especially when they involve a Disney vacation! A few years ago when my husband was on a business trip, our kids and I hopped on a train, a bus, then another train and showed up at his hotel by the Disneyland Resort! It was awesome and they were really surprised. Sometimes with teenaged kiddos, you have to get a little creative. You could do it where you don't even tell them where you're going until you get to the airport and then give them a Mickey Mouse-shaped luggage tag and see if they can guess!
Another fun thing we've done is go to WalMart or Target and buy a bunch of Disney-related fun things like stickers, water bottles, glow sticks, plush, and maybe a movie or two. We wrapped a separate package for each one of the kids with a Disney hooded sweatshirt on top and when they took out the sweatshirt, they saw all of the other goodies underneath it. You could make a little sign that says something along the lines of "You're going to Walt Disney World in 10 days!!" and put it in the box too! If you do decide to surprise them a little early, one last fun thing to add is a
Free Disney Parks Vacation Planning DVD! The kids can watch it over and over to get even more excited about the upcoming vacation!
I hope this gives you a few ideas, Tara! I have a feeling that each of us here on the Moms Panel would have lots of different suggestions, so please feel free to send in more questions! :)
Wishing you a Pixie Dusted vacation!
~Jackie