Both times I was upgraded on AF, I had an "M" ticket. The flights took place in 2003.

The first time, I was traveling with my father who was in his early 80s, so I flew out to California to meet him, and we were booked on the AF nonstop SFO-CDG (holding DL tickets on this code-share), connecting onto BUD. We were on DL's "wait list", and didn't clear within 24 hours, and the concierge at the DL CRC in SFO refused to clear us on the flight. We went over to AF in the SFO international terminal, arriving there about 75 minutes before departure. A very nice lady working at the AF counter checked us in. I told her about our wait list status. She told us that there was a possibility that we would be upgraded, and to go down to the gate and wait for an announcement. As it turned out J was sold out, but there were 5 empty seats in F. She was as good as her word. 5 pax were upgraded to F, and, of the 5 seats in J suddenly vacated, my dad and I were the last 2 people called to the podium and given upgrades from Y to J. They processed the mileage deduction at the gate (I was GM at the time). This was the most special upgrade I've ever received in my life. My dad and I proceeded to have an incredible experience on AF--the food, drink and service were impeccable.

Later that year, I was on a mileage run in December to make PM, and I was able to get an open jaw M itinerary for less than $1200 that got me just over 75k--IAD-CVG-LGW on DL, and then a code-share on AF MAN-CDG-IAD. On the day of departure from IAD, I learned at the DL check-in counter that my upgrade CDG-IAD had cleared, which I paid for in miles.