I just saw Roman’s TED Talk last week, and the simple rules for flag making that he laid out spurred me to make a design that reflects what’s iconic about San Francisco: 
1. two blue bars for the Pacific and the Bay, 
2. an orange red center stripe for the Golden Gate Bridge, and 
3. a Phoenix (style taken from the Univ. of Wisconsin — Green Bay) for heritage and rebirth.

Thoughts?