Singapore Airlines: RTW Flights (Open Jaw) Ex PER, ADL, SYD, CNS, DRW, MEL, BNE from $1809+

this is a bit of a niche and complicated "deal" but it could be useful for someone trying to book a round the world trip from any city Singapore Airlines flies to in Australia (PER, ADL, SYD, CNS, DRW, MEL, BNE)

this has been working for at least 6 months for me, probably longer but I found while playing around with multi-city flights that you can book a reasonably priced RTW ticket all with Singapore Airlines pretty much year round (although prices still increase in peak times). the main trick to this is the 2nd sector must always be between MAN (Manchester) and IAH (Houston).

you basically pick a destination you want to go in europe out of the following list (Manchester, London, Paris, Barcelona, Zurich, Milan, Rome, Munich, Frankfurt, Istanbul, Amsterdam, Copenhagen). then add a segment of Manchester to Houston (find your own way to Manchester but internal europe flights are pretty cheap). then for final flight choose one of the following cities in United States back to Australia (Seattle, San Francisco, Los Angeles, Houston*, New York**) once again you will need transport between Houston and whatever city you choose

the price generally comes out between $2000 and 2500 even in times where booking the transatlantic flight seperately would be $1500 on its own.

*a flight from Houston back to australia will go via both MAN and SIN
**if you choose to leave from JFK or Newark the price is more expensive as there are only premium economy seats on that route, I would still class this as a reasonably good deal though.

I couldnt find anything near as good value or as flexible as this even when going the cheapest airlines possible, allowed us to book a cheap family trip visiting rellies in both US and UK.

The cheapest I found was $1809 CNS-SIN-FRA ,MAN-IAH, SFO-SIN-CNS booking on Singapore Airlines directly using this(google.com) search on Google Flights

additionally you can extend stopovers in singapore by booking them as seperate segments and it doesnt appear to change the price ie (4 segment multicity, PER-SIN, SIN-FRA, MAN-IAH, SFO-SIN-PER).

you can also start from one aus city and end in a different one and it still works, it also works in either direction.

EDIT: FRA-JFK also works for the middle segment, which is probably more useful

https://files.ozbargain.com.au/upload/233963/110882/singapore_airlines.png