If we are gonna be deciding a symbol, i feel like good flag bad flag (pdf here) is good reading. It covers the positive characteristics of making a good flag. It takes the perspective that a flag should represent an "organization" to be seen at a distance, often moving, and reproduced in quantity at scale. This makes it's purpose overlap quite a bit with our needs.

1. Keep it simple: The flag should be so simple that a child can draw it from memory
2. Use meaningful symbolism: The flag's images, colors or patterns should relate to what it symbolizes
3. Use 2-3 basic colors: Limit the number of colors on the flag to three, which contrast well and come from the standard color set...
4. No lettering or seals: Never use writing of any kind or organization's seal
5. Distinctive or related: Avoid duplicating other flags, but use similarities to show connections.