Guys you have a variety of things to choose from. Wingtips or gangster shoes like spats and of course fedoras are awesome. Girls vintage dresses, shoes, hats, flowing skirts, hair in twists, rolls, and hair nets, forties attire. Swing is from the forties and believe me if you go to the right place and you dress up you will fit right in. If you aren't quite sure do some research or go dancing and then go shopping.
Swing dancing is very popular in some places right now.
There are quite a few places in Northern California, tons in San Francisco. The Top of the Mark, and there are many more. A good place to find great events is at Jump site where they are branching out to all over the world.