A colleague recommended the documentary "The Times of Harvey Milk" (1984) to me recently, and it was a great call. Yes, it's a wonderful and very loving biography of Milk, but it also offers some wonderful lessons in city politics and civic engagement. I'm actually using part of the film in my state/local politics class to teach about the consequences of a city choosing district-based or at-large council elections. As the film explains, San Francisco switched to district elections in 1977, making it possible for the Castro area to elect the first openly gay city official in the nation a year later.
You can view the entire film for free on Hulu or YouTube.