I managed to get an upgrade yesterday by pure chance (and a little white lie!). When I went to check in, the check in clerk told me this flight will be very crowded (a 777) too). When it came to asking if I would use coupons to upgrade,I got a brain wave and told her that when I confirmed my flight a few days before, they automatically upgraded me to Business class as they needed to sell my coach class seat. After about 50,000 key presses and a few huffs and puffs, she finally said begrudgingly 'I have no other seats so i'll have to give you that seat,' and gave me my business class borading pass! God it felt sweet.! I'm still owed about five books from UA so I don't consider this cheating just payback but the food and drink somewhow felt even better when i got it absolutely free.

I don't think I'll try it always but when I'm short on coupons, it may be handy.