If your brother loves Chuck-e's then he should enjoy WDW. My sister is developmental delayed, but is quite high functioning. With her, her likes run the gamete from stuff preschools love to something other 30 somethings enjoy.
When we went with her during the ages of 7-16, she was would ride anything. When we went for a half day when she was 18, she was resistant to some of the attractions she normally enjoyed. I took her and my parents when she was 31 and she barely did attractions, but enjoyed the shows and characters. Knowing this, I took here again the next year and we barely did any attractions, but she had a blast meeting characters and seeing shows and doing the attractions she did love. She is not big on the attractions at WDW, unless the queue is mainly outside, as she tends to panic if she cannot see either the loading or exit. We have not been back in about 4 years, we did a
Disney cruise instead last year.
So, here are things I have found that I did to help my sister, mainly based on her needs during our trip in 2010:
1. Since she was a early riser, we would go to the parks early, but not right at RD.
2. Take afternoon breaks, either at the resort for a long TS lunch.
3. Planned character meals at resorts for breakfast or lunch so she could look around at resorts she had not seen before.
4. Kept up with the character greeting times and show times and let her met the same characters over again at different places.
5. Willingly rode Small World, Jungle Cruise, Safari multiple times.
6. Drove to the parks instead of taking the buses as she has a slight fear of being left.
7. Watched the parades multiple times, luckily there were quite a few then.
8. Left before the fireworks started, even if we stayed late.