How important is it to teach our children manners?

I'm hoping we can all agree that it is imperative that we are teaching our young children manners. And I don't mean manners that are limited to "chow time". What I mean is teaching them the words "please and thank- you", "excuse me", teaching them to wait to speak or talk when adults are speaking and something that is very important to me: teaching our boys how to be respectful to girls and, teaching our girls how to be courteous to their peers. Gone are the days of showing respect to our elders and our peers. I know we have become a very self centered society but, I also believe we can begin to change this if we begin when our children are young. So, the next time you have a parent come into your classroom and your entire class goes crazy...Stop. Address the behavior and set the expectations. Follow up with a "thank you for showing Ms. Sarah respect while I was speaking with Johnny's mommy" or set an appropriate consequence when your classroom elects to continue their behavior. Teach your boys to allow the girls to go first, to open the door and to help when it is needed. You would not believe how much this inspires continued positive behavior and manner in your classroom. Your thoughts?