Etiquette for Opening Doors

Q: Does etiquette still dictate that men should open doors for women?
Full Question
I'm a young woman and I open doors for myself. Sometimes I open doors for the men Im walking with, if I arrive first. Every so often, a man will look amused. Does etiquette still dictate that men should open doors for women? When should a girl rush to open a door, and when should she pause to wait for someone to open it for her?

Answer
I think women are their own worst enemies. We had our men opening doors and then womens libbers came and burned the bra. For a man to say, After you, is wonderful! Of course youd open the door if a man had a heavy parcel or hands full. Its just courtesy isnt it?