Update on this...

Just got the SPG Amex card with 35k bonus. After hitting the minimum spend and getting transfer bonus for every 20k miles I transfer to Alaska Airlines I should have 50k miles to use through Alaska on the SGN to NRT flight. Perfect amount for two business class flights on Japan Airline or Cathay Pacific.

Japan is direct, but looks like the flight is the angle flat seats. Cathay would be a better business product, but not direct. So will have to weigh the options for when it's time to book in a few months.

Bonus good news is we'll have about 380k points/miles to use on the other two legs.