You'll get the Business Lounge unless you have Business Suite ticket which won't happen unless you have a flight on an A380. OZ doesn't use them on any of your flights so no Suite Lounge unless you've got at least OZ Diamond Plus status, *A Gold won't get you in.

That said the Business Lounge isn't bad for a 4 hour layover. I usually start at the one in the center for a shower, bigger buffet etc. and then head to one that's closest to whichever closest to the gate about an hour before boarding starts for a quick final bite.