You work at an accounting firm. A client emerges from her meeting, holding her squirming baby. She needs somewhere private to nurse her child. You would offer her:
The break room, which is currently empty but close to the boss's office, and has no door.
The office of someone who isn't going to be in until the afternoon...but has sensitive information sitting on her computer and on the desk.
The women's bathroom, which is private, but not comfortable.
I had this issue this morning. My coworker criticized me for my choice, but I still think it was the right one.