One piece of advice from when I went to Disney in high school: get your son a handicapped pass. I think you go to the information desk when you walk into the park and ask for one and explain why you need it. With the pass, your family skips the regular line for a ride or show, and enters the handicapped/special access line, avoiding waiting in the heat and sun. I can tell you that this pass was invaluable to me when I visited Disney!