In particular, Arisia gave people an incentive to use the stairs by having a "Summit Mt. Arisia" event complete with water stations, signs showing how high you'd climbed, and a ribbon for reaching the top. This meant that people who might not have thought about stairs but could use them were more likely to know about them and use them for the entire con, saving space in the elevators for those who needed them more.

This wouldn't work for every con or every hotel, but it's one example of the creative thinking that can be applied to access issues.