The only way to get to Australia using DL miles is with Korean Air and South African. However, South African awards are only available to Perth. SAA serves SYD as a code-share with QF on QF equipment.
From my experience, the easiest way to get to SYD using DL miles is to fly SQ to SIN. (95K for Biz if you fly transpacific). I would also recommend Malaysian which I have flown 4 long-haul sectors on this year. From SIN, you can fly to SYD for between $300 and $500 for a basic 60 day ticket. There are many carriers that fly the route including BA, QF, Emirates, SQ and EgyptAir. My last trip down was on BA. The cost of about $600 for a 6 month World Traveller Plus (which I'm a big fan of) was only $10 more than for a regular Coach ticket when booked directly through BA.
[This message has been edited by leroy11 (edited 07-09-2002).]