Makdyn,
Congratulations! And good luck on keeping the secret! I know exactly how you feel. Two years ago, we suprized our kids with a trip to Disney for Star Wars Weekend. I was going nuts for two months! There were times when I would just have to walk out of the room for fear of saying something. (DH threatened to put duct tape over my mouth!)
But, I managed to keep the secret and it was worth it. We met them at their bus stop after school and told them we were going to Disney World, TONIGHT! The looks on their faces were priceless! They felt they were dreaming when they woke up in DW the next morning. They never imagined that that weekend they would be in Disney!
We video taped it when we told them. We also have videos of them that weekend. Over and over you hear them saying that they can't believe they are in Disney.
Good luck. I know it's going to be a very long summer for you!
Enjoy!