In summer 2014 I used AF to fly throughout Europe on 8 legs. Now given it was Intra-European flying, but:

I was upgrade to FC 5 legs, BC on the other 3. The gate agent always assigned me the seat in BC, the 5 FC upgrades always came from the FAs on board. The FC was just the first row on the A320s and BC was the next 2 rows, so I'm not really sure what the big difference was. All flights were on A320s 1.5-2 hrs long.

Also a strike threatened to overbook a flight once, so the gate agent asked the CA and I got approval for the J/S Of course when it came time to push, there just happened to be a seat in FC, so I took that . Things have certainly escalated security-wise in Europe the last few years so don't expect that, but also don't give up on it and don't forget to dress at least half decent when you're doing it!