Over the weekend I ended up at the Vintage Expo here in San Francisco. This show features about 80 sellers, hawking everything from serious couture to simple little day dresses. Everything I saw was in exquisite condition, but usually had the pricetag to match. Still - if you are looking for a really nice, unique dress or suit for some sort of special occasion, this would be a good place to find it.
Santa Monica in February, April, October
San Francisco in March and September