Hrrm, I forget the exact flying time, but Los Angeles->Sydney has to rank pretty high up there. Felt like about 284 hours once it was over.

I think it was about 14 hours or so. I don't normally mind flying but I got going pretty stir crazy on that one.
The good side is that Sydney is one of the few places on earth worth being cramped up in a metal tube for 14 hours to get to! I'd do it again in a heartbeat! It was 2 years ago this week and I really, really want to go back to see more of Australia...