I once got to shoot the United retro colors on the A320 while I was at SFO up the tower but I had not got a decent shot of it actually flying.  When it showed up on approach to SFO, I was pretty pleased.  Sadly, the cloud cover was not cooperating terribly well.  Only when it had got past me did it pop into better conditions.  It was okay when further out on final but neither of these were too helpful.  One day!