I've only been upgraded once, flying VS from Hong Kong back to Heathrow. I consider that one to be good karma for agreeing to a work trip to Taiwan at short notice (which meant my employer had to pay for a full-price ticket). It is nice to have a seat where you can lie flat
I was muttering about being unable to check in on-line for the flight from the hotel in Taiwan but the pleasant surprise at Hong Kong more than made up for that.
Of course, the downside is that my next longhaul was paid for by me, so it was behind the wings and a lot more cramped after the enjoyment of being up front.