All I can add is that they don't come to ORD very often. In all my visits, I've only seen a couple -200s there. Dissapointingly, there aren't even that many -300s around at any one time (it's one of my favorites to watch). I can only recall seeing 767 domestic flights to SFO, DEN, and IAD from ORD. They go to Europe and South America mostly. ORD has pretty much been taken over by the 777; there are always 4 or 5 there at any one time.