Upvote:1
Have you tried using the Round The World fares offered by the alliances? Both SkyTeam and Star Alliance (probably One World too) offer Round The World fare calculators. You simply input your stops and they let you know routing and fare. You would need to add one more stopover, as most RTW fares require a minimum of three stops (maybe spend a night in NYC or ??).
You can also try the multi-city option on Fare Search engines, though that often gives you some convoluted routings.