The house has a pretty large backyard by San Francisco standards.  There is a sandbox for young ones and lawn games for older kids and grown ups. 

 
 

We went to the members' pre-opening of the California Academy of Sciences and think that visitors will very much enjoy the exhibits at the academy.  The architecture alone is worth seeing - see the website of the Academy to get an appreciation.  Kids (and parents) enjoyed the T Rex skeleton, a great whale skeleton and several marine exhibits.  There is a swamp and an African wildlife exhibit to name a few.  Our son's favorite though was the two heads snake - I guess my favorite too.  The Academy within a mile from the house so about a 15-20 minute walk or very short drive.

 
 

We love the live performances put on by the Buddy Club.  The exhibits are also terrific.  This is very close to the house - either a long walk or a short ride.

http://www.randallmuseum.org

 
Kids' Symphony 04/27/2008
 

The symphony also caters to kids - and the kids really love it.  Check out the schedule of events.

http://www.sfskids.org/

 
 

Two tops picks close by are (in order of proximity):
1. Grattan Playground (about 6 blocks away at Stanyan and Grattan)
2. Children's Playground at Golden Gate Park (see park map)

Other playgrounds close by that we like alot:
Rossi Playground (Arguello and Anza near USF)
Julius Kahn Playground (in the Presidio)