Just a reminder to have all of your flight information and contact phone numbers readily available on your phone in case you need to reach the airline quickly.
A few years back our flight returning from Greece was canceled, it was the only flight of the day for our airline. While everyone rushed to the ticket counter and stood in a line with only 2 agents, we sat down and made one phone call and we were rebooked immediately on another airline, arriving home an hour later than originally planned. When we stood up to go to the the new gate, everyone in the very long line asked us, what did you do, how did you do that?
Its very simple if you have all of the information handy and readily available. You may not always get out so easily but at least you won't be stuck in line for hours waiting for someone to help you rebook.