I believe it is called the Autistictraveler.com. I don't know anyone that has used them but they help schedule trips for kids/people with Autism..

Since I live in So. Cal, I know several people who have taken their kids to Disneyland. Go to Guest Services and they can issue a disability pass. We have done Legoland several times and had a great time! My 4yr old loves roller coasters and high intensity rides, but goes on overload real quick. We did a sharing system of my choice/your choice. That worked great so I could get him to do slower activities. Frequent snack breaks also help calm things too. I do only have one child, so that makes it easier to tailor activity around his needs. Keep your expectations low, pace activity and have fun!

When we went to Disney World, I brought a letter from the doctor regarding my son's autism (and consequent problems with over-stimulation and waiting) to the Customer Service area inside the park and were all given special passes for shorter wait times (for free). It helped tremendously. Check out Disneyland's website. They probably do the same thing there. I hope this helps!

Thank you for expanding my horizons on this topic. It is something I need to research and read about so we can expand the possibilities for our son's activities. Well, I guess my son is on the moderate/severe end of the spectrum too so and so he may have alot more issues. We're working on alot of them so I will definitely keep this in mind because one day he will be ready for this! Thanks! :)

Honestly, unless your 2 younger children have no sensory issues and no issues with tantrums and having to wait in lines, it could be the wrong time for a Disneyland trip. You should call them and ask if they have an Autism night or disability week because if they do - then the lines would be shorter. My 7 year old moderately Autistic son processes sounds and sights different from other people and until we are able to teach him how to process these outside events he will meltdown and have alot of challenges. If any of your Autistic children are prone to attempt to wander or are hyper wanting to unstrap themselves and climb out of seats on rides - this is not the right time. Well, you know your children better than I do - but I am personally having an anxiety attack over here just thinking of the thought of taking my son to Disneyland! I can also imagine since Autistic children often have a set amount of time they can remain overstimulated without having major issues, it's not going to be really enjoyable for your older children if the younger ones are interrupting their plans by needing alot of breaks or resting time due to behavioral challenges. If they are not processing these events well, they are not going to get anything out of this or enjoy it. The other thing is and again I don't know your children, but many Autistic children suffer from ear infections and fluid behind the ears. On an airplane that can cause an immense amount of pain with the pressure changes especially while landing. The other thing is WOW how sensitive airline staff are in pulling the cord on your trip if they see your child throwing a fit and if you are not perfect in dealing with that in public - they might quickly assume abuse and kick you off the flight. These things do happen to good parents. You are FAR more brave than I and I wish you at least 3 helpers if you really do this! :)