It's not a new lounge in BKK. The Turkish lounge is fairly new (next to the SQ lounge) and Thai has just opened a new lounge, which is, by all accounts, very nice and a 100% improvement on its previous offerings.
Just ask at check-in for the SYD SQ lounge, or look for the signs.
Lounge access is on departure for the airports you have mentioned. There aren't many arrivals lounges on the star network.
I had never thought Turkish lounges or Thai lounges would be as good as the larger airlines as i guess i just always assumed the airlines that had a better rep for flights would automatically have better lounges and more money but that is probably not the case is it? Is the thai lounge very busy being i presume their main lounge as its in BKK