Shopping advice please!

I'm going to San Francisco this week for a couple of days. It's mostly a work trip but I do have a few hours for shopping. Do any of you have favourite boutiques in SF that you'd like to share with me? I really need to add a few key pieces to my wardrobe and I'd love some advice from my lovely readers :-) I need some fun, chic/stylish clothes that I can wear to trade shows and to speaking engagements. Advice please!