I'm no expert on this, but based on my EWR-OAK flight last week, I'd think you might have better luck with a mid-day flight into SFO. Problem is so many of their flights are on 737s, which only have 12-14 seats in first. The 757s don't have any more than that from what I can tell. Don't know about the 767s.

Last week the EWR-OAK flight had a waiting list full of golds that didn't get upgraded. I don't know if this is typical or if bonuses on that route combines with low fares caused it to be fuller than normal.