I frequent SFO - FRA and always apply a GPU; my chances of upgrade have been hit or miss as a premier1k. I'm curious to hear about the experiences of other flyers on this route or other long haul routes when it comes to specific days of the week with a higher chance of getting upgraded - all things being equal. Friday and Sunday seem very steep and I'm now leaning twords flying Saturdays (I only fly weekends.) Thoughts anyone?