Good for all of you, it is SOOO much fun.
We did that a few years ago when DVC held a special weekend for members to celebrate the opening of SSR.
Our oldest 12 at the time knew she was going to miss two days of school for a long weekend trip, but never mentioned it to the younger two and had no idea of what for.
That morning we sent them into school with notes that we were picking them up an hour early. The look on their faces. All they could do is keep asking why, why, why????
They whole way to the airport they are guessing what we are doing, where we are going.
The look on my middle daughters face when we got to the gate at the airport and she saw Orlando. Everyone looks as they all started screaming and jumping up and down.
I would do this again, but not for a while, they even agree, being surprised is great, but the anticipation is half the fun, too.