*****About Waiters*****
if you dont say thank you, they think youre arrogant, though theyve grown accustomed to it.
if you say thank you theyre pleased, but they feel theyre owed that.
if you say thank you, turn your face to them and smile in gratitude as you say it, youve probably made a friend for the rest of the meal, and a Kiddush Hashem as well.