So what is it like traveling with him?
Vacationing with him has been generally successful. We always fear that he will have an explosive bowel movement at an inconvenient time, but although that fear is not unfounded it has rarely occurred (he did get a new set of socks at Disney, so rare doesn't mean never). Still, this is what we have done with them.
A cabin in the woods, on the bank of a river. Since he was with us the whole time, there were no problems. He enjoyed the playgrounds at Callander and North Bay.
Turks and Caicos
We enjoyed a stay at Beaches Resorts in Turks and Caicos. The kids program staff was wonderful towards our son. He would run towards the kids area every morning. The only problem we encountered was immigration and customs. Our son hates waiting in line and ended up bawling inconsolably.
Steve melts down in lines, so we obtained a pass that allowed us to skip the lines. That helped, but the heat and the walking made him grumpy and whiny. Dark rides scared him, fast rides thrilled him.
This was a short fall trip. Christmas decorations were out on the Canadian side. The hotel had a nice pool. This was an easy excursion for us to make.
Seattle and Vancouver
He liked the Space Needle. Would have enjoyed swimming in Vancouver, but the pools were closed due to a city worker strike.
Nickelodeon Resort (visited Orlando amusement parks other than Disney) and Sarasota
Big breakfasts and pools at Nickelodeon. He did well at Sea World and Universal. Loved swimming at the beach in Sarasota. Fun trip.
Stayed at the Beaches Resort in Negril. Had a babysitter the whole week (for about $200) who helped him participate in kids' activities and took him swimming. He had a blast. Same melt down in immigration, though.
Lots of walking and looking at things beyond his understanding and interests, but he did well to endure it knowing that he would be rewarded with pool time in the evening.
He enjoyed swimming in the pool and the ocean.
Boston and Acadia
Lots of walking in Boston during a heat wave, but he liked Riding the Ducks. Also enjoyed Lulu the Lobster Boat out of Bar Harbor.
Yellowstone and Grand Teton National Parks
No swimming, but horseback riding and boating were his favorites. He generally tolerated the hiking.
Edit: you can cross off Cedar Point from the things Stephen can't do. He has been able to enjoy riding the roller coasters there with his special needs high school class using their virtual line system.