I do not know how much money you are looking at spending so I will propose this which would be nice in Biz, but not sure in steerage. (FYI- MH C/J is excellent). The seats are not as nice as WBC but the entertainment and food are in a world by themselves.

SEA-NRT (NW)
NRT-KUL (MH)
KUL-SYD (MH or Qantas)
SYD-KUL (MH)
KUL-SIN (MH)
SIN-NRT (NW)
NRT-SEA (NW)

also, it is fairly easy to book award seats on MH in biz and first if you are looking at doing that.