I've been inspired recently by the 1970s/1930s vintage vibe, and stumbled across the wonderful Goodwood Revival classic car show. There are a lot of classic car shows out there, but Goodwood is particularly fun because of the vintage fancy dress from all eras! Wartime land girls, 1950s glam, space age 60s... all there, with the cars to match.
Also found some great old posters at grandprixhistory.org which I enjoyed browsing through. Proof that not all fashion inspiration has to come from fashion!