Here is a question: if I need to go from A to B (say, SFO to BOS) and I am willing to fly with 1 stop, I have lots of stop choices (e.g. ATL, DTW, etc).

How do I figure where I have the highest elite upgrade chance? I do know that *in general* less business'y routes are more likely to give a mere Gold an upgrade while crossing a major hub is less likely, but what are some other ideas - time of flight, specific airports, etc

Any/all tips are appreciated?