It depends on the agent but some charge much less than others. With the agent I use, I save costs doing most of the hack work, researching availability for the travel I want, then advising them of those flights etc.. They then provide further input and once agreed, book it.

In arranging my most recent one, their fee was ~£125. During the process I was advised that by using JL*JL on the last segment, rather than the codeshare xx*JL I had requested, fuel fines for the entire itinerary would decrease by £250-£300.

Quick question on ticket validity - I did read the excellent blog. If I understand right, ticket validity is 12 months from the first date of travel. So a ticket issued in December 2025, with the first flight in March 2026, would be valid until March 2027?

Yes, all travel on the ticket must be completed within 12 months of the first flight.
However, seeing as the ticket would have been issued in Dec 2025, you would not be able to choose flights past a certain date (prob Nov 2026).. so you would have to change dates after starting travel to last into March 2027.

That's really helpful, thank you.

Correct, and it's not clear if any date in March, or just March. My last trip was March 10 2024 first flight, and March 10, 2025 last flight. So actually a day over a 365 day year.

Were time zones - date line coming into play? How did the last departure time/date compare to the local time where the first flight happened. (all in GMT zulu time)

I would assume this would been after a rebooking once travel had commenced.

With an xONEx, booking, ticketing and commencing travel on it the same day is conceivable but unlikely, and not possible when departing from TC1..
Even with that, transits can be had up to days after (e.g. LAX-xSYD-BNE with LAX departure on the "last day").

As far as I can tell, if an agent or airline makes changes to a booking via a GDS, there is little up front constraining them from making changes not compliant with the fare rules.

[Quote; "Even with that, transits can be had up to days after (e.g. LAX-xSYD-BNE with LAX departure on the "last day").
As far as I can tell, if an agent or airline makes changes to a booking via a GDS, there is little up front constraining them from making changes not compliant with the fare rules".
Quote: "Were time zones - date line coming into play? How did the last departure time/date compare to the local time where the first flight happened. (all in GMT zulu time)"]
*****The flight departed SYD to HND, which was the first and last city in my itinerary. There is a two hour time difference between SYD, UTC+11 and Tokyo, UTC+9. I don't know for sure if the schedule is the same today as it was in March, but likely JL 52 departing 0855, arriving 1745.
(Apologies; I couldn't get the multi quote button to work, hence the weird format.)

If you have a TA-issued ticket I'm assuming all changes prior to travel need to be arranged with the TA. Once travel has commenced can you just go to any OW airline or does it have to be the one the whole ticket is plated to?

... And... Let's say certain segments are using the code share, rather than the OP carrier, is there any way to make sure that sticks? I've read that BA, QF and AA are sticklers for making you use their prime flight number where that's relevant. I'd be looking at date, rather than routing changes.

Why wouldn't you use the TA for the life of the ticket? Are you trying to avoid fees (I suppose it depends on your arrangement with the TA).
I would view this as if you booked with an OTA like Expedia. My experience is that the airline won't (can't?) take control of the ticket unless you are flying that day.. but even then it depends on the airport staff. This is all very hypothetical so perhaps you can share what exactly you are trying to achieve.

Re: codeshare
What do you mean by "sticks"? Sometimes the airline will discontinue codesharing on that route even though the flight is still operating.

Mainly thinking of trying to give my TA a quiet life and also to avoid additional fees.On the second point I appreciate that a CS can discontinue. Was thinking more of the re-issuer pushing it to the prime flight number, even when alternatives exist.

I personally don't see the value in trying to alternate between TA and airline ticketing desk, but YMMV.
You have to realize that voluntary ticket changes require effort, regardless of whether a TA or airline does it.
Voluntary changes can be avoided completely.. it's just a matter of planning.

Not if part of your ticket is for further ahead than can be ticketed at time of issue.

OK. One change. Good luck with your choices!

Even though I have only flown 5 RTW's in the last 20 years, the complaints about the AA RTW are misplaced. Sure there can be an occasional bad agent, but the pluses far outweigh the neagtives.

1-A dedicated desk that is open 12-14 hours every day, not some general ticket sales desk.
2-Changes are usually done within 24 hours, many times sooner.
3-The only cost is the $125 fee for change in ticketed points. Plus any extra taxes and fees that a change may incur which you would pay anyway. I received a refund of those same taxes and fees when those fees decreased. Show me any other discounted fare that has those provisions.
4-AA does not charge a local service fee that JL and QF do charge.
5-A and D class are much more open than other discount fare inventory. Most issues seem to be point of sale/commencement or married segment restrictions. A TA may have better results, but not the 1 time that I used a TA instead of AA.