You are missing a trick on NRT-HKG - BMI miles. I am doing SIN-NRT one way on BMI miles next month, and for a paltry 15,000 miles + £105 + tax I get 7 hours in Singapore Airlines first class! You can buy 15,000 BMI miles for £200-ish.

Not sure what the maths is for HK but presumably similar. Do a BA open jaw (HK and NRT) and then buy some BMI miles to do the hop inbetween.

Biggest problem if you open jaw will be HK availability. Historically NRT has been a doddle but as BA has gone for 2 flights a day to 1 this may dry up.

Its a shame you don't have a stack of BMI miles as Asia is the best use for them - I'm doing F from NRT next month on Swiss for 25k one-way plus a bit of cash plus taxes.

Have you considered paying 100% cash for YVR? Air Canada is showing £1,743 each 1-8 July in J, although you need to be careful to get the new Executive First seat, and BA £1,807. This is a better deal that £1.1k + 40k miles, when you factor in the extra miles earnt back and the 240 TP's.

There may also be some benefit in holding on and seeing if any sale fares reappear on this route. Business travel starts to drop in July anyway.