I'm dual homed in Chicago and NYC and fly back and forth about 40 times a year. Been doing this for about 10 years. I'm also an EXP. I fly to LGA late afternoon on Sunday and fly back to ORD on Friday morning. I have seen the CK pre-boarding at LGA and ORD a handful of times recently. I usually buy my tickets 3-4 weeks out to minimize my costs. Upgrade rates are about 80%. Many times I am the last upgrade at the gate. Although often it clears at 100 hours. It does seem to usually be the Friday morning LGA-ORD that does not clear. From my experience in F on that flight, it seems to have a fair number of paid J customer connecting to the PRC flights at ORD hence fewer seat available for paid upgraders.

I did fly for a couple years as a 1K on UA. Upgrade rate was about 40% on UA. UA did have an upgrade priority system that rewarded travelers buying more expensive tickets vs. AA's which rewards flyers who buy their tickets earlier.

I have noticed upgrade percentages have dropped. I went 18 months in 2008-2009 without missing an upgrade. I assume the drop in upgrade percentage is a combination of capacity discipline and the improving economy.