@spivonious: I've tried not noticing people's differences, and just treating everyone the same. It always comes back to bite me in the *.
I was raised to be polite to others. Part of that is holding doors, giving up my chair to others, etc. 95% of the time that works fine. Most people are appreciative and cool with it. Recently, however, there have been people who actually get upset. It's women and the handicapped to be specific. It has nothing to do with race, gender, or capability. If you are close enough that it won't be an akward wait, then I hold the door.
That doesn't bug me as much as when people use their electric wheelchairs to ram their way through crowds. I got my legs bruised up once because I stood my ground.