A clean bathroom

It's cherry blossom time in our nation's capital. The savvy traveler knows that the cleanest bathrooms near the Tidal Basin are those adjacent to the Meyerhoff Theater on the Concourse level of the Holocaust Museum. Those adjacent to the Rubenstein Auditorium, on the other hand, I could not recommend on an April afternoon.

The most useful tourist guide to many cities would be the one that revealed the cleanest public restrooms. Of course, that would increase their use and negate the benefit.