There's understandably more focus on where best to start an DONEx or AONEx, but after several of those I'm considering a LONEx as a way to get from the UK to Australia in late Dec via a stop in the US (I'll use miles to get back from Asia). I have an expert flyer account but have no sense of which places are cheap for starting in economy. Any pointers?

So far I have (priced in USD via expert flyer for ease of comparison):

UK:
LONE3 2342.96
LONE4 2733.46
LONE5 3319.20
LONE6 3904.94

OSL:
LONE3 2093.68
LONE4 2480.65
LONE5 2877.58
LONE6 3274.39

NRT:
LONE3 2971.79
LONE4 3145.66
LONE5 3715.17
LONE6 4302.44

(LONE3 prices for more expensive places than OSL: ARN 2152.01, AMS 2425.10, CPH 2420.19, PRG 2596.25, KUL 2690.61, SIN 3403.43, PVG 3482.35, HKG 3630.30, JFK: 3599.00)

The choice of route and plating carrier would have bigger impact.

You may misunderstand LONEx rule.
Your simple LONE4 route from UK will be LHR-JFK-SYD-HKG-LHR.
So, what do you mean "I'll use miles to get back from Asia" ?

If you want to visit US and AU from Europe, you have to use XONE4 products.
Threfore, it automatically includes flights from AU to Europe (via Asia).

I think he means lone3 Europe USA Asia.

Mileage Asia to Australia.

You make it sound as if you've had enough of flying the Premium cabins and want to try something different...no problem with that it's just not very common here on FT

Do they still have seats in the back of the plane?

Yep. Though that's mostly destination independant as I expect the route to be similar regardless of where I start and will fly AA enough to have them ticket.

Apologies, was unclear with the background info. Basically I need to be in Canberra over XMAS and flights from the UK to there are understandably very expensive over that period (~$2k+ in economy for dates I want) and of course award bookings into Australia are very tough just pre xmas (I have flex in Jan for a return so that is less tough). Plus if flying in economy for some or all long hauls I'd want to break up the journey (love biz class of course but I travel OK in economy on a single long haul if it's mostly a day flight, two back to back though....).

So I'm pondering options. E.g. either nesting a ticket within another (e.g. LHR-SIN and SIN-CBR), and wondering if getting there on a LONEx and then using the rest of the RTW later in 2019 has more value. If I did a LONEx it would probably be Europe USA Australia Asia (nest return to London) Europe as I may have reason to be in the US in Dec.

Also I was just interested in what the prices were for its own somewhat nostalgic sake. My first xONEx over a decade ago was a LONE5 (I've done maybe 10 DONEx RTWs since but always from somewhere very cheap and expected that last one -- ex-CAI -- to be my last for a while at least as over time the time away is harder, the travel is worth less and the mileage value has reduced with AA's changes so I'll likely let EXP slip from 2020).

So.... I assume nobody knows if anywhere beats OSL by a non trivial amount?

Not sure I've had enough of it, would happily fly premium for economy prices .

Thankfully cheap business class returns seem to crop up fairly often for trips I know I need and can plan months in advance (did EU-Asia return for ~$1300 earlier this year and have EU-South Africa booked for not much more next year). The big change is much less travel for the sake of travel or EQD/EQMs.

have you started your ex-CAI yet?

Done and dusted!