Originally Posted by
VegasGambler
You should always book a seat you can tolerate but unless you are based in a major hub upgrades should be pretty common. Not 100% but there are lots of people here who report 90%+ upgrade rates.
I typically book coach to Hawaii and PE to the mainland. When F can be had for say $350 more than PE, I buy F. But sometimes F can be many multiples of that.