Adjoining the windy bay on the sunny side of town, San Francisco's downtown district provides unusual visual expansiveness and fresh air in a hyper-urban locale.
With a lot to see (including iconic Transamerica building) and a surprising amount to do - the Embarcadero and/or Yerba Buena Gardens provide good starting points.
To go further afield, investigate the JeJune Institute :)
Eating options are plentiful, mundane and tend to be expensive - demand surpasses supply. Red's Java House is a fun bay-side exception to this rule. The Union Square area provides much of the city's best high-end shopping.
Union Square, North Beach and Chinatown are within easy walking distance, MUNI and BART also provide faster and cheaper transportation options than driving.
Wikipedia: http://en.wikipedia.org/wiki/Financial_District,_San_Francisco,_California