BKK does not have have good connections to Australia both ways. Usually you need to wait 18 hours in one direction or another. In fact I can get to Australia using TK and Air China with an extra stop, talking a few hours longer in one direction and a few hours less in the other than the LY BKK and HKG connections, and I frequently do. (also the service is better and the frequency and there are backup flights, none of which LY provide.