I say we do away with all pretenses at being polite. Let's call our bathrooms, restrooms, or whatever you call them, biological rooms. The reasoning is quite simple, we perform basic biological functions in there.
When you go to the "rest room", it's usually anything but. If you're not doing the pee pee dance, you're doing the poo poo dance, washing microbiological life forms off your hands, or wholesale washing off your whole body. We even scrape off fur, take medicine, and generally address other biological needs there.