I also recommend UA, but depending on where you are flying, flying coach on another STAR Alliance airline might be a better option (NH, SQ) as they will give you more room and better service.

It is my understanding that Econ Plus is not available on most UA trans-pac 777s ... which, is what UA flys NRT-JFK non-stop and many intra-Asia routes. All UA 747s have it but then you will not have a PTV at each seat.

All that said, UA, no matter what configuration, is better than NWA ... at least until they start putting their new A330s into NRT. In addition, on intra-asia routes, if you restrict yourself to NWA, you will be stuck on narrowbody aircraft to many destinations leave yourself with only one flight a day on which to accrue NWA miles. With NH (ANA) you have tons of choices out of Tokyo to get your UA miles.