My daughter has been going to car shows and cruises with me since she was little. Give each of your kids, if over age 2, a cheap digital camera. They will take all kind of pictures of what they like, and keep some distance because of the camera's focal range. Those photos will give you a whole new perspective on shows and cruises (kids' eye view) and some of the shots will be absolutely incredible.

I'm posting the shots my daughter took today at the Gratiot Cruise in a different thread.