Hi guys, thanks for all your great advice. Sounds like I should definitely commit to AA, and that if I sign up for the platinum challenge when I know I have Perth flights coming up then I should safely hit platinum before the end of the year.

Just to confirm:
- I want to use the points to redeem in business or first on OW int'l flights, not necessarily on QF or AA metal
- My fares to ADL, SYD and BNE are usually B class (sorry I'm not sure which classes earn points and at what rates - would be great if someone could clarify)
- I'm interested in whether status with AA gets you access to domestic QF lounges (surely they must give you access to int'l QF lounges)

Thanks guys! I signed up already and have flown once - still waiting for the points to show up in the account - will let you guys know how I go over the coming weeks.