You know the one who empties your trash, makes sure there isn’t water dripping on your head and in general keeps the building from falling down around you. Be especially nice to them.
Make sure you visit her office or work space. Not just so you know where to find the extra tissues and garbage bags, but so you can show that you appreciate what she does every day. Because you probably couldn’t do your job very well with a trash can full of yesterday’s lunch and water dripping on your head.
However the next most important reason to be nice to the maintenance staff is so that if you ever lose something, they can keep an eye out for it.
I once lost a small diamond earring. The earrings had more sentimental value than monetary value and I was upset. I tore apart my car and my cubicle and house to no avail. Just when I thought all hope was lost, I came into work to find the earring taped to a post it note on my desk. The cleaning staff found my earring! I wrote a thank you note only to find out that in several years it was the first thank you note they had ever received.