I can only speak for myself, but this is not the simple issue it once was. I was raised to respect this particular tradition, and very rarely sit on a bus at all, I am usually the first to volunteer my seat. I have though, on one occasion been read the riot act by a woman who was offended that I would assume she couldn't stand simply because she was a woman, belittled and accused of being sexist in front of my own children, and on another occasion, was roundly chastised for holding a door for a woman. (a holdout habit from my boyscout days). I still do both these things, but while doing them am on the lookout for attacks.
Drew