Thank you all for the replies so far. My thought was to fly westbound but I wanted to make sure that I was not overlooking something.

A couple more questions:

1. If I choose to upgrade to Economy Plus off an Economy award ticket, is it refundable if I end up cancelling (or switching to different flights)?

2. Is the partner airlines award seat availability limited to what I can see online or will more options appear if I call?

3. Do you have to go through immigration at NRT if only to catch a connecting flight to SIN?