I had a very nice battlefield CPU experience on MSP-SFO (L fare).

F on the 737-700 was booked 10/12 before the upgrade windows. At the GS window, a couple was upgraded and F was booked full. It remained that way until about T-48, when someone changed/canceled and it went to 11/12. The buy-up offer then appeared as follows:

Within booking: $537
OLCI: $429
Kiosk: $429

I was #1 on the waitlist and stayed there, waiting with bated breath for someone else on a higher fare to bump me or for someone to bite on the buy-up. Another thread discussed how the EUA process might run within 3 hours of departure now, whereas it wouldn't before. I was very pleasantly surprised for my upgrade to clear 50 minutes before departure. ^ 14 names were left on the waitlist at boarding (including a few non-revs), so it wasn't the most elite-heavy flight. Still, I considered the upgrade to be quite a bonus.

Moral of the story: Even if F is booked full before nearly anyone gets upgraded at the windows, anything is possible!