I usually upgrade on international J and assign a $/h value to the upgrade. I then take into account modifiers such as direction of travel, outbound vs inbound, and night time vs day time, and what I need to to on arrival.

I will not divulge the range of hourly rate: even though "AC Top Tier" may not frequently post here, I am sure flyertalk is frequently monitored , only to increase the bottom line for AC based on the consumer opinions posted here. I think sometimes people in this forum forget that.