Opening the door for others is not only a sign of good manners, but it also says you are a polite person. In a world where the hustle and bustle of life tends to make people a bit testy, small gestures bring a smile to many faces.
Momma always told us to open doors for those older than us. It was a sign of respect for the knowledge they held at their age. Ladies, while mom always said that gentlemen should open doors for you, you should always defer to the age rule when in doubt about who opens the door. Saying thank you for the open door with a genuinely happy smile completes the experience in a positive light for everyone.