We went on a 3 day Disney Cruise a couple of years ago. We used to have a two-day fall-break like time frame in October in the schools so we scheduled it then, which happened to also be over Halloween. We packed for the kids who were 5, 3 and 1 at the time, so they didn't know.
We picked them up at school on Wednesday and the first thing they noticed was that I was picking them up along with my wife. The kids asked why and I said I just wanted to get them ice cream. Well, two hours later when we arrived at the airport, the oldest said, "I thought we were getting ice cream?" The middle kid says, "I want to go on an airplane." So I said we could do both. At that point, my oldest kid starts crying, balling in fact. We didn't tell them where we were going yet, but she had made all these "plans" with her friends for Halloween.
So we flew into Florida and still didn't tell them anything. Upon our arrival near port, my oldest starts yelling things we're going to do, "are we going fishing? are we going to the beach?" She's still kind of upset as APPARENTLY, she hates surprises. As we get closer to the terminal, my younger child yells, "I SEE THE DISNEY CRUISE SHIP!" "Let's see if we can get on it," I say. "REALLY!!!!!!" they shout. We had a very fun three days.
And I guess my oldest doesn't really hate surprises anymore. We surprised her with a birthday present that was pretty nice this year for her ninth birthday. We took her to the Olympics in London. We had a birthday party for her and her last present was event tickets to diving (we didn't have the gymnastics tickets in hand yet, which would have really made her flip out) and copies of the boarding passes. She went crazy excited and started balling in a good way. She still thanks us for the trip half a year later. We actually left the next day after her party and everyone at her party knew but her (including her now six year old sister who kept the secret for the two weeks we had been planning the trip).