"ORD-JFK-SYD is more base miles than ORD-LAX-SYD although I guess maybe not so good if you can do the AA sector in First whereas the JFK-SYD would be in D all the way."

Thank you. That's an interesting idea. @:-) Do you know if it would be legal given that I would have already done the one allowable transcontinental trip (LAX-SJU)? Do they realise that NYC-SYD is via LAX and so I would in effect be doing two transcons?

There's one way to find out I suppose...