As far as shopping goes, Union Square is great for chains such as Diesel, H & M, Zara, DSW, Urban Outfitters, Old Navy, Forever 21, Aldo, and many more. But when you want stylish boutiques, head straight for the Union Street shops (on Union between Steiner and Octavia.) Stores include: Ambiance (which has 2 locations on Union), Brown-Eyed Girl, Mingle, Blue Jean Bar, Bebe, and LF. This area also has many great restaurants, especially Left at Albuquerque and Capannina. The Route 66 margarita (a 54oz. drink) at Left at Albuquerque is sure to make your head spin!! Share one with your favorite shopping partner!
My other two recommendations for shopping areas include Fillmore Street in Pacific Heights and Hayes Valley. Shops to visit on Fillmore include: Metro 200, Shabby Chic, Kiehl's, Riley James, and Gimmee Shoes. My favorite boutique in Hayes Valley is Azalea at 411 Hayes St. They have the best selection of designer denim and trendy tops in the area. Flipper's at 482 Hayes St. is a great place to stop for lunch and have a juicy burger. I would also recommend the following places in Hayes Valley: Modern Tea, Nida, Ver Unica, Dish Clothing, and Flight 001.
Two other shops worth mentioning are Ab Fits at 1519 Grant Ave. and American Rag at 1305 Van Ness. It's also fun to hit the Gilroy Outlets (on the 101 hwy at Leavesley Rd.) on the way there or back for reasonably-priced merchandise and sinfully greasy garlic fries.