Which reminds me of a situation which happened to me last year. I was waiting at the gate to board SFO>SEA and was #1 on the upgrade list for 1 seat. A DL Captain (in uniform) showed up and I overheard him telling the GA that he would take any seat as he was flying the SEA>HKG leg after arriving at SEA. Apparently he had been called up as a last minute replacement for another Captain who must have been unable to go to HKG. After I boarded and was in my seat, the Captain was the last to board. I got up and asked him where he was sitting and he said right at the back as it was a full flight. I insisted that he take my seat as he needed to get to the S Concourse as fast as possible once we landed at SEA. I also mentioned that I was on his SEA>HKG flight and would see him on board as I always go up to the cockpit to say hello to the crew. Once everyone had boarded and the boarding door had been closed, the Purser came to my seat and said that I could take the last seat in D1 at the Captain's request! I was so thankful as I had no GUC's left and had no other way to get into D1 for this flight. It just goes to show that once in a while a good deed can sometimes be rewarded!