Good schedule would be good choice in your case.
I believe you travel in Coach.

Since I'm both NW and KE elite, I might helpful for choosing.

KE Vs NWA
<FOOD>
KE: offer food for human. (Worth $50)
NW: Is that a food?
<AVOD>
NW: VERY neat & Nice AVOD system ^
KE: Randomly AVOD aircraft in SEA (it's very boring when it doesn't)
<INTERNET>
KE: Sattlelite high speed internet for only $26.95 ( only on Tue, Thu, Sat day)
NW: Isn't your AVOD is Enough????
<FA>
KE: Enjoy beauty of Asia 20/30 club members
NW: Grand ma why are you here???
<transfer airport>
KE : ICN wow 3rd best airport in the world ^ ^
NW: NRT carpets gets stinky
<world club>
ICN: YES, NRT: YES
<arrival time in BKK>
very relevant to what date you travel, same or less then 30 minutes difference.
<seat selection>
NW: Grab the EXIT LOW with shiny GOLD card 90days before on NWA.com .
KE: IT's on your luck SEA-ICN but you should get ICN-BKK portion when you check in @ SEA (they just got internet seat selecting service but EXIT and some other seats.)
<inflight amenty kit>
KE: just started from Jan 30. 2006 (Almost everything you could find in busniss & First class form other airline)
NW: where's my tooth brush??
<ticket>
both E-ticket :-:
<what to expect canceled or delayed flight?>
NW : protected by rules they gives you voucher (if meets condition)
KE : NADA ~~ sleep on airport floor.