Hopefully not a silly question, but thought I'd ask: is Chicago the only place you want to go to on this trip? The reason I ask is that at least with Qantas Points you can often get more bang for your buck booking a OneWorld award which will effectively allow you to travel around the world for slightly more points than a return business ticket to ORD. This also has the benefit of breaking up the trip so that you can find availability. For instance, you might find availability to say Japan no problems, then a couple days later there is a flight to Chicago available with JAL. Another popular option for breaking up these flights is routing via Honolulu. The benefit there is you aren't dealing with a massive airport, and you get a nice little mini-vacation in paradise.
Personally, I wouldn't bother booking a cash ticket for part of the trip and then an award ticket for the other bit. What if you face a delay on one of the tickets and end up misconnecting? If you have everything on one itinerary you are protected in those instances.
If seats are available for SYD > LAX or SYD > SFO are you concerned that you'll never find availability on those routes or do you not like connecting through those airports? IMHO those two airports are arguably some of the best in the world for OneWorld flyers, especially if you are flying business. Great lounges at both airports (Qantas J and American Flagship at LAX whereas SFO has a really nice Admirals club). LAX has the edge IMHO as they always have the shortest security lines anywhere since you get to shop around and find a TSA checkpoint with no queues, clear that checkpoint then just walk to the gate/lounge.
Thinking in terms of OneWorld (the alliance Qantas is part of) your major hubs in the east of the Mississippi would be Chicago Orchard Field (ORD), New York (JFK) and Philadelphia (PHL).
If you are doing a marathon, I would argue the less time you spend on a plane the better. Don't get me wrong, I enjoy flying, I've got Platinum status and just yesterday I took 4 flights for no reason other than to earn status credits. But flying does have an impact on your health and performance. Remember, the cabin of most airliners is very dry, you are losing a lot of fluid on a flight, and that's before you put your hand in the liquor cabinet. Now I am not an elite athlete by any stretch of the imagination, but what I do find is after I take a long trip, I don't perform as well cycling compared to before I left for a sojourn like that.
That's a possibility, and supposing the airline chosen supports OSS it is a very simple transit process. Essentially you clear TSA security and US pre-clearance then head to the gate. Since you clear much shorter immigration at Vancouver instead of at a major airport in the US, it means no long queues.
The fewer connections the better and I suspect there won't be much of a non-stop option on OneWorld at that time.
It's a possibility although it will add extra travel time to the itinerary which may or may not be optimal if you are about to run a marathon. With that being said, I do hear that JAL has an excellent J product these days.
Having flown to all of the QF US hubs now internationally I would tend to agree with your assessment here on DFW over say LAX or SFO. The immigration lines aren't as chokers as the former and it isn't a labyrinth to navigate like LAX. The security queues can be a bit longer though at DFW, especially if you don't have TSA pre-check like yours truly as the queue for non pre-check was 25 minutes when I was there a couple weeks ago. Meanwhile the pre-check line which was backed up all the way to the AA check-in desks that I joined cleared in 5 minutes. Now that is fast!
-RooFlyer88
