For a HKT flight, the regional lounge is likely to be the best bet. I haven't been there since it was refurbished but it was already comparable to the international business lounge. It's compact, there are showers, it's close to the gates, and they have cake - what's not to like?
Oh and so you know, there'll be no lounge access on the HKT-BKK leg, though I'm not sure where PG are flying from since they built the new terminal.