I have a small office with only two floors. The bottom floor are our 2 financial people, the original owner of the company (now he's chairman of the board and just writes his books all day while his wife runs the company) and then storage, the break room, two bathrooms, etc. I was here a good 8 months before I knew one of the doors led to a (very small) shower room! Actually, it wasn't until after my first company holiday party, where my gag gift was a map of the building did I notice one of the rooms was a shower, and it took me another month before I remembered to verify.
I'm the only one who uses it. Occasionally, one of the ladies here will go kayaking early in the am and use it as well, but it's mostly just me.