Dan Vasser, his wife Katie and their son Zack live in a large Victorian house in San Francisco. The location of the house is unknown but may be located in western or central San Francisco somewhere between Golden Gate Park and the Financial District. This is implied by the episode where Dan Vasser walks from Golden Gate Park to the Financial District in 1987.
However, this is unlikely as the view his street provides is not available in any residential area of San Francisco and no area of Golden Gate Park provides such a close view of the Golden Gate Bridge -- that segment was likely shot in the Presidio.
Wikipedia states that this house is on the same street as the house used in Charmed which, although supposedly in San Francisco, is actually in Los Angeles. Perhaps this house is as well (with a computer generated view of San Francisco in the background).