Finally got on FR late...but glad to hear Rita has been downgraded to a category3.
Democrats with last names toward the end of the alphabet would probably scream "discrimination" at your idea...though they'd be the first ones to evacuate.
When there's a fire drill or building evacuation, people line up and go out in single file, they don't all rush for the door to get out first (unless they are George Costanza). So I think some kind of finely tuned evacuation procedure would be appropraite for evacuating a city.