Piglet,
Last year on our honeymoon, my DH and I were chosen as the Grand Marshalls for the Share a Dream Come True parade at MK. It was wonderful. I don't think that there is any "magic" to getting picked. There simply was a man (Fred) passing out maps right as we were going on Main Street and he started up a conversation with us. He asked if we were on our honeymoon, how often we visit Disney, yada, yada, yada, then he just asked if we would be interested in being in the parade. And of course we were!!! But as I said, we did nothing to get picked, we just happened to be lucky that day I think!