As an Aussie who doesn't live downunder anymore (but who is in Australia every month) the problem we have is that the Oz market is a 2 horse race. Both airlines need a heavy investment in the lounge network. About the only lounges worth visiting are the QF First pubs in MEL and SYD. I visited the Virgin lounge in MEL the other day and its underwhelming to say the least.

The QF Business lounge (International) is average at best because its in the basement and has zero windows, the Amex Centurion lounge is small, SQ's is better and Plaza Premium ok (catering for all 3 lounges is done by the same people). The Air NZ lounge at MEL International terminal is decent as it has views to the apron. I havent been to EK's lounge at MEL international for a while but it used to have great views of the airport, plus the best food and wine options.