Bizarre Guitar has a great selection of new gutars and amps, especially on the high end. They have a full stock of Gibson and Martin acoustics, which is pretty rare. I'd imagine the selection is the best in the Valley They carry relatively few used instruments but you can ocassionally find unusual, cool used stuff. Prices are ok - don't expect any great deals. They used to be much more competitively priced.
They lose points on customer service. You can't touch a guitar without asking permission and if you do ask to play they hover over you, If you're just going in there to buy strings or a cord, expect to be treated like an annoyance.