The Cradle of Forestry in the Pisgah National Forest in NC has an adventure zone that was specifically made for kids with autism. They worked with the Autism Society of North Carolina to design and develop it. I'm looking forward to taking my grandson up there in a couple of weeks.
My brother & fam went to Pigeon Forge, TN & Dollywood. They said theme park was great & their child got to ride the rides unlimited
I like to take my son to the beach down south. I find the water and sand give my son amazing input and he is just amazing.
We took Nick to th NYC aquarium for his birthday. He loved it and it wasn't super crowded like other places like that, but I personally thought it was the worst aquarium ever. I was able to call in advance and get a lot of info about the theater and everything else available to him so we could talk about it prior to visiting.