Originally Posted by
pandaperth
Longest is JFK-SYD, which is 9,961 miles
There's no such non-stop. With a stop in LAX, yes. But if you start allowing connections, then for instance PER-DFW would be longer (10,000+ miles).
The longest non-stop flight is SYD-DFW, but certainly not the cheapest.
OP is asking an essentially impossible question, by stipulating two competing criteria without specifying a way to combine them - is it cents/mile, or what?