Hi
Kay!
When your family arrives at any Disney Theme Park, head over to Guest Relations and ask for a Guest Assistance Card (GAC). As you already mentioned, a GAC does not guarantee front of the line access at any attraction. GACs are in place in order to accommodate Guests with a variety of special needs through alternate attraction entrances, where available. Be sure to obtain the
Guide for Guests with Disabilities brochure which will explain the services available at each particular theme park.
My biggest tip when traveling during the summer, and especially when traveling with a special needs child, is to arrive at the theme parks for Rope Drop. Return to your Disney Resort Hotel for a mid-day break, then go back to the theme parks for dinner and evening fireworks. If you choose to remain in the theme parks the entire day, be sure to keep him hydrated! Bring whatever toys, electronics, or reinforcers work to keep him occupied. My son loves the Little Green Aliens (LGA) from Toy Story and we always bring a LGA themed item to keep him occupied.
If your six year old can't tolerate loud noises, bring ear plugs or noise cancelling headphones. To take a break from the hustle and bustle of the theme parks, consider the following. At Magic Kingdom take a ride to Tom Sawyer Island. At Disney's Animal Kingdom ride the Wild Express Train to Rafiki's Planet Watch. At Disney's Hollywood Studios stop by the tables and chairs area near Echo Lake, or sit on a bench in the quiet stretch of Pixar Place across from the empty Soundstage One. Epcot has several open spaces and water fountains that can help anyone refocus.
Try to maintain his regularly scheduled meal times. In addition, alert Cast Members about his diagnosis and request to be seated in a quieter area of the restaurant, if at all possible. This will go a long way in ensuring an enjoyable vacation for the entire family.