Shopping in California? I know of Self Edge.
Looking at your route, in San Fran you've got Self Edge and Union Made (think they have a few locations there).
In Santa Monica there was Fred Segal which carried a lot of good stuff, but think that's gone now (the one on Melrose is still there and is worth a visit - next door in a converted mechanics garage is RRL and just down the street is APC). I think that the outdoor mall there (Santa Monica Place) has a Barney's coop and the department store next door (forget which one it is) stocks some decent brands that you don't find at others (APC, OL, Gitman etc).
If you go into LA then you have quite a few decent stores although they are quite spread out. On La Brea there is Union which is probably the best all around store (imho), Undefeated, Stusssy, American Rag, Steven Alan, Unis (I think) etc all in close proximity.
And on Fairfax (short drive from Melrose and La Brea) there is Flight Club, Supreme and Canter's Deli which is always worth a trip for food (park in their lot if you going to eat as they validate with a food receipt).
If you buy records then you should definitely head to Amoeba, that place is unbelievable.