Kristina Chew of autismvox.com often describes the ocean as her son Charlie's home. I think in many ways, Disneyland is Patrick's. Not out of any particular love for the characterst, but for those familiar rides that he associates with important things.
At Disneyland, things don't change. Star Tours is Star Tours. It will be the same ride, with the same dialogue, and the same environment, today, tomorrow, and next year (until they update it, as rumored).
At Disneyland, things are predictable. The train will always go from Main Street to New Orleans Square to Toon Town to Tomorrowland and then past the dinosaur diorama (which terrified Patrick until we named the dinosaurs after characters in the show Dinosaurs).
Life isn't predictable, as Patrick has had to learn as he's gotten older. Sometimes things don't work out the way you plan them -- for instance, your dad isn't here to see your high school graduation -- but at Disneyland, things are always the same. And if they do change, it's easily predictable and takes a long time (say, the construction of the Nemo subs).
Ironically, our trip yesterday involved a lot of unpredictable things. The first ride is always the train, which broke down. It's a Small World broke down (the motors that keep the current going stopped, and the boats drifted lazily back and forth in the silent room -- they turned the music off -- while the characters still moved and danced...it was eerie). We then went to the Jungle Cruise, where the microphone didn't work. After dinner at the Plaza Inn to watch the fireworks, Patrick and I went over to Space Mountain (for Patrick's first ever ride in California; he rode it in Florida and loved it) -- which, yup, broke down as we were about 9 trains' worth back in line. (It restarted shortly.)
But it was still Disneyland, the place where Patrick seems most comfortable.