With the chatter about dress code in the lounges....

I always wear casual when travelling EXCEPT when I am on standby to be upgraded.

I find the upgrade succes rate to be MUCH higher when I wear a shirt and tie. A genuine "good morning" to the GAs with a nice smile does wonders as well.

A nice thank you when you do get your upgrade is always appreciated by the GAs AND they just might remember you the next time you are in line for an upgrade....