Go on Korean Air.

All flights are low level redemptions and layovers in Seoul are good.

80k round trip for miles in Y.

You have to call and ask for availability. If you find the seats you want you can buy the miles that you lack and then book it. This assumes you are traveling with others and not just by yourself.

120k miles gets you biz class on Korean.

Getting to ICN-BKK is easy. Finding seats across the Pacific is the hard part.

Foo