BOS-SFO
 

Anyone have success with upgrades to either First or MCS? It doesn't seem like there are many seats available. Any suggestions on which flight times have best success? Thanks.

Can't speak for SFO BOS however things might have changed with AA off the route so fewer premium seats in the market.

Virgin is adding another frequency in the market however starting in March:

VX 350 SFO BOS 7:35A 4:15P 319
VX 355 BOS SFO 5:15P 9:05P 319

Success upgrading to F in Feb 11
 

I flew BOS-SFO on the 8 PM flt. As AA pulled out of the market, VX was the only choice at this time. I was able to upgrade to F in the 6 hr window fairly easily.

Not sure if my experience is an indicator of F availability. I understood from the FAs that someone important had booked a couple of seats in F and cancelled in the last minute.