However, a 'reversed color' standard is pretty interesting.
Take an image of a current US Flag. Change the red stripes to blue, and the blue field to red. Intriguing.
I also like the simplicity of the CSA National flag, currently still used by Georgia. I could see instead of a single 'national flag' (since we are technically a confederacy and not a unitary nation-state) that we use a design similar to the present one, but instead of a canton of stars, each state would put it's own seal or design there. (like what Georgia did with the old CSA flag)