May I have some advice regarding layovers.

I'd say do LAX-MEL-PER - the walk around from intl to domestic will stretch your legs and yes the MEL lounge is better than BNE (and I live in BNE). 

The BNE biz lounge only has 2 showers and the size of the lounge means its crazy busy in the AM. I've no doubt MEL will be as well but its at least 5x bigger!

The MEL lounge gets pretty cray by about 0630. I was there on Saturday morning and had to queue for the showers (by standing in line with pancakes).

Smartgate will be your saviour, saving you quite some time in not having to queue for passport control.

Enter your passport into the nipp** high machine, push it hard into machines "mouth", wait a few secs, answer a few questions, out pops a receipt, keep that with your passport and IPC, enter your receipt into the mouth of the camera slot, go look at the camera with the bright lights, gate opens, take back receipt, and then go to baggage retrieval, find bag, pick up bag, and then go for AQIS/DAFF, if nothing to declare and non popped, go to near the exit, hand in IPC and Smartgate receipt, and thats it!

I have done MEL and SYD incoming from NZ, MEL wins hands down for sure.