cant speak for others but personally if I know about staff travelling on the flight in plenty of time and we have enought meals on the flight will try and upgrade where possible.
Personally think the best person to try and get an upgrade from is the dispatcher (especially with the airline I work for).
Have found that American Airlines are very good at upgrading especially on internal US flights as me and a mate got upgrade on 2 out of 3 flights even when we were wearing shorts in the scorching heat (excellent service aswell)
good luck