Each child on the autism spectrum is so different from each other they all have different reactions in the same circumstances. I have two boys (18 and 10)with AS and they're very different and I have another 10 yr. old with HFA (they're twins). The only one with crowd issues is the twin with HFA and I deal with it in different ways like removing him from the situation if need just for a little while for him to calm down or giving him something to distract him like Pal Mickey, for instance. Pal Mickey is a Mickey Mouse doll that will periodically start yakking and give info about the park or messages about a line thinning etc. It amuses him and if you squeeze it yourself, it will talk. As for the rides, the boys actually do really well on them. Better than me, actually.
The GAC is worth it's weight in gold, it was an incredible life saver for us. The first time we went, we didn't know about it and when we went this past August and had it, the vacation was so much better. There is no mention of the disability on it.
On another note, Bubba had asked how kids w/AS were doing in school. I've had some really horrible years and some ok years and some stuff in between. I'm currently getting an advocate to fight for some tutoring for my autistic son and last year had to have my AS twin removed from gym because the teacher was bullying him. It never ends. You can write to me privately if you need to and believe me, I know how awful it can be. Take care and have fun in DW, Christine