The front entrance to my company’s headquarters has really heavy doors. When I was pregnant, I was really worried about the strain of opening these doors and was very thankful to people who helped me (I work for a very chivalrous company, so its not really an issue of not finding help).
Judaism is very respectful of women and middos are an important part. I think most men who want to be nice and respectful find ways to do things within halacha (including opening doors).
My rule of thumb is to help everyone – so if a man needs the door opened, I will (many men have trouble with this). If an old woman needs help – I do it. And yes, my husband often opens the door for me when practical. [Sometimes people think I’m into women’s lib, but I don’t know if I agree. Different topic, different day]