QF's surcharges on LAX-SYD are significantly higher than AA when booked as part of a DONE4. I know what the fuel surcharges say, but the difference between booking AA and QF on this routing is about $1200 US cheaper on the AA side.

I wonder what AA is planning on SYD-LAX.
I have P class seats ex SYD late Sep and exLAX mid Oct. The AA code shares on QF are still showing open availability, but there are no business seats available on AA and limited W/P class. I wonder what the on departure upgrade opportunities will be? Or even if I will swapped over to the AA code shares on QF?
Interesting times to be wandering
Fred

For AA*/JL flights, you have to call AA to get seat assignment. JL has a strict policy (unlike most other airlines I know of) to not help reserve seat when marketing carrier is not JL.

You used to be able to do it via the JL website but you had to use the JL flight number. Another quirk was the naming convention. I believe it to get it to work I had to use FIRSTNAMEMIDDLENAME with no spaces for the given name field.

But you have to have a JL prime flight in your PNR, and even then I recall some problems, although I don't remember the specifics.

Call AA for seats on AA codeshares on JL, (and possibly for JL prime seats)
 

Thanks very much for this ernestnywang.
I tried calling JL and they assisted me to get seat assignments (perhaps because I am Oneworld Sapphire) but gave Mrs Jrobin seats that were across the plane from me in one AA codeshare, and could not assign a seat in another AA codeshare. On the JL flight they also had difficulty assigning a seat for her. I suspect it was because she has no status.
Later JL called me (while I was on the phone with AA) and said I should talk with AA about seats on codeshare flights and not JL.
AA were able to assign seats on the AA codeshares on JL and even on JL41 on which the JL agent was unable to assign a seat for Mrs Jrobin.

I just got off the phone with the RTW desk and that may explain the 2,500USD taxes/fees/surcharges on top of 5,415USD base fare.

My current itinerary on hold is OSL-xLHR-JFK-SEA-xLAX-SYD-HND-xDOH-OSL. This was meant as a placeholder to fulfill 4 continent requirements until I figure out the final routing. Would doing LAX-NRT-SYD-HND save me taxes/fees? Any other options I can try to minimize taxes until I'm ready to do the final routing?

Your taxes will reduce significantly if you can find availability on the LAX-SYD AA flight.

I will try. Does QF charge onerous fees on Asia-SP D fares too? Like SYD-NRT?

Alternatively, is there a way to determine what fees/taxes will be charged per segment without sending the whole itinerary to the rate desk?

ernestnywang has been very gracious in helping users identify costs. One way to estimate would be to use the oneworld RTW explorer tool and make a change to one segment to identify the relative cost difference.

I don't know your exact carriers of choices. Given your LAX-SYD seems to be booked on QF, I assume your LHR-JFK is on AA. This is the closest quote I found that match your numbers.

The QF 1145.00EUR YQ + 12.50USD YR is very high and can double if you put SYD-HND on QF as well, so yes, you can avoid it if you do LAX-NRT-SYD-HND and do not use QF at all. Use JL for NRT-SYD-HND. In this case, LAX-NRT is cheaper on AA, and if you can use JL for HND-DOH it would be even better. JL's YQ is higher for SYD-HND (219USD + [3.6USD per sector]) alone but lower when SYD-HND-DOH (67EUR + [3.6USD per sector]) is put together. But as you can see later, as long as you can use AA code for LAX-SYD, that would save you more.

Yes, and remember not to use QF code (use JL code instead) for SYD-HND, and also use JL code for HND-DOH.

I have previously shared that in some cases using AS code for TPAC can further reduce YR/YQ, but in this case it makes no difference.

The 420USD YQ from QR is unavoidable as long as you have a QR sector (OSL-DOH). Given that and having to use some AA sectors at least, I think the last itineray is quite well already in terms of saving YR/YQ.

Yes, another 1145.00EUR YQ + 12.50USD YR is applicable.

Thank you!

Thank you for such a detailed breakdown. I switched LAX-SYD to AA flight yesterday and booked the fare since I need to fly the first 2 segments soon. Here is the itinerary with carriers slotted in:

OSL-(BA)-xLHR-(BA)-JFK-(AS)-SEA-(AS)-xLAX-(AA)-SYD-(JL)-HND-(QR)-xDOH-(QR)-OSL

The taxes came out to about 1,220USD. I am guessing, based on the above, majority of that is from the BA and QR charges?

Do you mean to use JL codeshare or actual JL flights?

Hmm my calculation is 1321USD, not sure where the 100USD difference is coming from.

Out of which:
BA - 250EUR=268.2USD
JL - 3.6+219=222.6USD
QR - 420+16+16=452USD

There's also a 16.46EUR Miscellaneous Surcharge counted as part of fare, not part of taxes. I believe that is AA's fuel surcharge.

As long as marketing carrier is JL, JL's YQ/YR rate will be used irrespective of operating carrier.

In my OSL-xLHR-JFK-... itinerary the first 2 flights were booked as AA codeshare (instead of BA prime). Is it required that the first flight and the first overwater flight be codeshares of the booking airline?