I agree wholeheartedly about being polite and friendly. I always make sure I smile and say hello,please and thank you when dealing with people. I also make sure I mean it. It always amazes me when I see people throwing tantrums or are rude and bullying that they expect to win. I work in a customer led public organisation and know that I am far more willing to go out my way if I am treated like a human being by the person wanting my help.
If there has been some sort of failure in service and I am making a complaint I make sure that I try to remain as calm as possible, be polite and reiterate that whilst I am annoyed/angry abou the situation reassure the person dealing with me that I do not hold them personally responsible and neither is it their own fault. I am very well aware that the Check-In Agent/Customer Service person doesn't have to help me beyond a certain level and in fact can really screw me over if I treat them badly. I have a friend who is a Check In Agent with an American airline and if you piss him off he will mark your profile with the need to have extra security screening done.
Even so being polite and pleasent will usually only get you so far. That was why I had wondered what extra's had come about in addition to what help I would expect from just treating the customer service/check in/cabin crew like human beings.