I missed a few flights, from what I can remember:
As a CO Plat, I missed:
CLE-EWR (#6 on the upgrade list, G fare)
SFO-EWR (#3 on the upgrade list, W fare)
EWR-SFO (#23 on the upgrade list, W fare)
Would have missed IAH-SJC (G fare, used buy-up to 1st from #4 on the upgrade list)
As a 1K, I am 100% on UA metal so far using instruments and UDU.
As a CO Plat flying on UA metal before achieving 1K status, I missed:
SFO-DFW A319, #1 on upgrade list
Several ORD-SFO's
SFO-EWR on UA metal
SFO-SAN on UA metal
I think that's it. We'll see what happens in 2012. I definitely feel like CO metal I had crappy luck compared to what I got on AA with transcons on hub-hub routings.