As you correctly spotted I am using BD miles. I have approx 600k for the two of us to spend.
It all seems like quite a chore to redeem miles as many airlines either fly to where I don't want to go (eg many of BD's flights) or have few available seats on many of their popular routes as I guess they are going to fill them with more profitable fare paying passengers.
I like the idea of going back to Japan but the reviews of NH's beds is that they slant rather than lie flat so you slide off them of don't sleep!

I'll continue my research.
Thanks guys