Welcome to AFF.
It is not clear what points you have, but I will assume Qantas points.
Be prepared that you will need to pay additional taxes and fuel fines (and I would expect this to be almost $1000 pp).
Getting 4 award seats on the same aircraft is likely to be tough (and Im not sure if you have enough points in any event)
(eg. a Basic MEL-JFK return in Economy all on QF is 128,000 points plus $844.62 - more if you need to include other oneworld airlines - so at most you only have enough points for 2 tickets)
You also ideally want to be booking 12 months out, as most of the award seats for Sep 2015 will have already been snapped up.
That said you are best going through the call centre who can look at flight options on other oneworld carriers that wont show on the online tool.
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With the prices of around $1000 for trips OZ-USA recently it would barely seem worth using points for economy flights once fuel surcharges started to be applied...