I fly the HKG - BKK flight around once per month... Its only a 2 hour 40 min flight, so always fly Y (around HK$1500 - HK$2000 normally).

Business is rarely full on this flight, so I always wonder why they dont sent out upgrade emails for these flights?. I would probably upgrade for HK$500. I know for EK its not a lot of money, but every little counts surely?

I have only seen the plane full departing BKK once and I was nicely upgraded that one time.