How to get the best value award flights to New York using Qantas Points?

Hi,My family and I (2 adults and 2 young boys)are planning to go to New York in June.I have around 550000 qantas points.I was just wondering what the best way to use these points would be so I get the best value for my points.Cheers Matt

2x J Aus> NYC via HKG on CX @278k points return ea…

Then put the boys back in economy on cash tickets? Or are they too young?