I have flown 2 round trips between ord and hkg in the last year. I had no trouble either time upgrading with an swu. However, each time I checked sfo to hkg and the availability was much less. Obviously, it is more reasonable to expect people in sfo to go to hkg than from the midwest. Also I think you are competing with more 1k's for upgrades. Despite the fact that ord is UA's home, I am sure there are more 1k's and Prem. Execs on the coast than here. Thus, I think you are better off leaving from Chicago.