Sutro Project / Union Square
Union Square hosts most of San Francisco's prestigious merchants (Barneys, Saks, Neiman, etc), and the rest are a few blocks down Powell street at San Francisco Centre.
Union Square adjoins the overlapping Gallery and Theater districts. Otherwise, Mark Hopkins or Harry Denton's Starlight Room offer panoramic views and libations. At night, Ruby Skye and Slide are often busy. Aforementioned Starlight Room can be quite a meat market on hump day's night (Wednesday).
In the winter there is an outdoor ice skating rink in the square itself.
Wikipedia: http://en.wikipedia.org/wiki/Union_Square,_San_Francisco,_California
