No problem for you to use The Wing (business class side, you won't be allowed into the first class part of the Wing) or The Pier. For business class I think the Pier is better, but you should use whichever one is nearest your gate. Both are much nicer than the other airline lounges in HKG. The noodle bar serves remarkably good food. This should give plenty of motivation to earn QF Platinum and get into the F side. CX is very diligent in meeting their Oneworld obligations, more than their partner airlines.