I'm a big tall guy, and I have a hard time fitting into the car booths at Sci-Fi Dine In. When we were there in January, I asked for a table car (with the standard chairs). We were told that even though we had a reservation, those tables were held for walk-ins and it would be a 45 minute wait. That was during the slow season on a slow day around 11:30-11:45am for lunch.
So if you require a standard chair, I'd suggest stopping by when they open and ask if they can hold a table car for your reservation time. I'm sure they'd try to work something out for you. Especially if you have a physical disability.