How Would I Express My Thank You To Cafeteria Staff?

Buy them something or give hugs or kisses

By continuing eating the food

Write them a thank you card

No matter where I am, in a checkout line, restaurant, drive thru, where ever, I ALWAYS make a point to find out the name of the person serving me and thank them using their name.  This usually shocks them because they are not used to being thanked in the first place. They also appreciate the effort I make by adding the personal touch of calling them by their name. It makes me feel better too, because I am acknowledging other people in my life and what they are doing to enhance it.