In about 10 years being TG*G, I had two op-ups from Y to C, once in Frankfurt and once in Bangkok. Until two years ago Thai had a reasonable standby upgrade fee for about 600 eur, but that is finished now. I have been flying Emirates to Bangkok for less than two years now and I had three op-ups from Y to C, one free R/T ticket for a denied boarding in Dubai (waiting three hours in the Dubai lounge sipping champagne) and one very nice upgrade offer from C to F on 2 legs for 50% of the miles. Emirates still has reasonable standby upgrade prices Y flex to C at about 450 eur per leg (so 900 eur for BKK-BRU). The quality of the Emirates lounge is way better than Thai C-class lounge and even better than Thai's F class lounge, better food, excellent wines and quiet.