Ever since my liberal use of please/thank you earned me a brownie from business class when I flew UA Y JFK-NRT at age 13, I've stuck with it ever since. The only time it seemed like I said the word thank you too many times was on my flights in LH F, as each little bit of food is placed on the table one at a time, yet I still found that I couldn't stop saying thank you for each item (and my F/A's reply "You are most welcome" probably got old for her too, but training/manners prevailed).

I am of the opinion that the better I treat airline employees as a passenger, the better they will treat me. This has worked out for me in all classes of service that I have flown.