The best option IMO is to transfer your points into British Airways' Avios points and redeem for Cathay Pacific awards, for the best combination of seats, routing, and schedule.

For the absolute best seat, you'll want to transfer into Aeroplan (Air Canada) and redeem for Singapore Airlines. Good luck finding availability. You'd also have to backtrack to get to SGN from SIN.

Also noteworthy is Japan Airlines' new J product, which you can redeem Avios for as well. I personally prefer JAL over ANA.

And if you like Hello Kitty then it's Eva via Aeroplan.

And yes, Chinese New Year and Tet will make it more difficult. Perhaps split into two parties of two?