Christep,
CX's First Class lounge in BKK is probably the best lounge available. Beats TG, SQ and other airline lounges by any standard.
As for your Diamond tier status recognition, don't expect to receive such recognition immediately. If you want to rush your status upgrade, I suggest that you call The Marco Polo Club service centre and get them to do a retrocredit for your HKG-BKK before you depart from BKK to HKG. Ask them if you could get them to upgrade your tier status from Gold to Diamond so that you can utilise your benefits on your return flight.
My simple theory is: If you don't ask, you don't get it. Therefore, it does not cost you to ask for a favour! Bear this in mind as it is a useful tactic if you want something done.
I think you will enjoy the vast benefits of Diamond card membership from The Marco Polo Club. It is a great program allowing members to utilise their Business Class lounge when flying on other airlines. This goes to show that CX really cares for your loyalty.
I personally have enjoyed Cathay Pacific for the last 8 years I have been flying with them. I rank them as one of the best in the world for its product and service innovations.
SQ comes second as I find their lounge product in SQ not up to the standard of CX in HKG. Also, I find their cabin crew to be too robotic and I blame their management for this. Other than that, SQ offers a good product but wish if they can fix a few problems with the new Business Class product which looks like a BabyPram.
A close 3rd is Emirates and then British Airways and Virgin Atlantic for their product innovations in premium cabins. EK needs to improve its First and Business Class but has a good Economy Class product.
Overall, we have 5 to 6 really quality driven airlines but two are based in Asia - CX and SQ. Well Done!