I was upgraded to first as a GM a few years ago, on ATL-SFO which was operated by a domestic config 767. Caveat: it was on July 4th.

Otherwise, I've flown ATL/MSP/DTW-SFO many times a year as a PM for the last two-three years, and I think I've only scored a free upgrade twice, both times out of MSP, once on a 767, the other either a 737 or a 757, I can't remember which.