Public restrooms in New York are few and far between. If you find yourself in need of a restroom, head for Midtown department stores, museums, or the lobbies of large hotels to find the cleanest bathrooms. Public atriums, such as those at the Citicorp Center and Trump Tower, also provide good public facilities, as do Bryant Park and the many Starbucks coffee shops in the city.
Restaurants usually allow only patrons to use their restrooms, but if you're dressed well and look as if you belong, you can often just sail right in. If too self-conscious for this brand of nonchalance, just ask the host or hostess nicely. Be aware that cinemas, Broadway theaters, and concert halls have limited amenities, and there are often long lines before performances/screenings and during intermissions.