If you're in the San Francisco (specifically Palo Alto) area you might like to check out my favorite historical garden, see website-

http://www.gamblegarden.org/

The house can be toured and the garden is always lovely. It has both formal and informal gardens.

Also on Waverley is the Ford Sculpture garden with a Southwest style garden and buildings, open occasionally.

Here is a link that might be useful: Gamble Garden