There are several threads about communication books - links to them are in the disABILITIES FAQs thread. Some are very complex and took a lot of work, but others can be very simple.
Most people find that using Fastpasses and going when the park is not busy is actually more helpful than a GAC. Because the GAC only helps with attractions, you still have to deal with waits for other things and just the general busy- ness of the park. Using Fastpasses gives you a more consistent experience than using a GAC does. Once you get into line, you will be in the attraction usually in 10 minutes or less.
As others mentioned, he does not have to be involved in getting the Fastpasses. Send someone else in your party with all of your park passes to the attraction. They will be able to get one Fastpass for each ticket. Then, just before your Fastpass time, you can prepare your son and let him know he will be riding soon. I don't think anyone
posted a link to the Fastpass page on this site yet, so here it is.
Even during busy times like Spring break, there are parts of each park that are busy and other parts that are very quite. We have gone over Spring break many times and my husband has gone early to the park with other members of our party while I got our DD who is disabled ready. By 10:30am, they were able to ride everything in Fantasyland, Haunted Mansion, Splash Mountain and Big Thunder Rail Road.
We have also seen at Epcot, Spaceship Earth will have very long waits in the morning, but if you wait until late afternoon, you can walk right in. IF you can walk in, you will get in fast, but if you need to use the accessible entrance, you will be waiting probably 1/2 hour. This is an example of the longer wait for using accessible entrances that was already mentioned. The same thing happens at AK - but 2pm, all the early riders are starting to go back to their resort. Many attractions there will have a very short wait in the last few hours before the park closes.
Services like Tour Guide Mike are also a good way yo avoid the crowds.