In reality, this is the Gamble House: http://en.wikipedia.org/wiki/Gamble_House_(Pasadena,_California) The house is owned by the city of Pasadena. Tours are available and the garage is used as a gift shop. The driveway is off-limits, but I was able to gain permission to drive my car up to the house.
This house is at 1711 Bushnell Avenue in South Pasadena: http://goo.gl/maps/9uGGd
This house is just two doors down from George’s house on the same side of the street. You can also see the tree that George fell out of: http://goo.gl/maps/V7lTo
Marty’s house is out in the valley, pretty far away from the houses above: http://goo.gl/maps/YNwFC