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.

 
 

The California Academy of Sciences includes, among other things, a 25 foot deep aquarium, a rainforest, a planetarium featuring real-time data from NASA, an early childhood center, an observation deck, an African exhibit including penguins, a swamp and an ongoing lecture series.  Check out the website: http://www.calacademy.org/

The California Academy of Sciences is within walking distance of the house in Golden Gate Park and the academy will be opened on September 29.