Most of the cons, you can buy a single day pass. Depending on the layout, most of them are in a single building. Dragon*Con is now in five different hotels. Three are very close to each other. The next one is about ten-fifteen mins walk away. The newest one is up a very steep hill. We took a taxi to it. Not a long ride, but the walk would have killed me.

Forgot to say, most of them have handicap services. You can check the sites to see what services they have.