It's your big day out and about in The City. Museums, shows, public monuments, the whole thing. All of a sudden you get the call. We're talking about the Call of Nature here. Sure, there are those who think of New York as just a big public urinal, but that's not your style. You want a bathroom with all the amenities, like a door and all that. With that call urgently ringing in your ears—and other body parts—there's no time to waste.
Check out Diaroogle, which bills itself as The Premier Toilet Search Engine. Bring the site up on your smart phone or computer, enter an address, cross street, or neighborhood, and check out the list of public and almost-public restrooms. There's generally directions, a description of what to expect, and for some of them even a photo to check out what you're getting into. And if you know of a great heretofore undiscovered necessarium, they've got a Submit tool to add yours to the list. Good luck!