I'm guessing you checked all transpac routes that worked for your dates?

I simply will not play the SWU roulette, and on a trip that I just got back from on Saturday, booked only on flights that had W availability, and made them work.

I'm on the East Coast and did EWR-NRT (with R > 0) and HKG-EWR (R9, actually). When I was booking my ticket, the EWR portion worked okay on departure (originating at DCA), but on return, I actually had to drive back home from EWR to DCA, but that was okay, since I could confirm my SWUs at booking.

But, from the West Coast when I was looking for my dates, SFO-ICN, SFO-NRT (2nd flight) and SFO-KIX were all available with R > 0.

Naturally, further connections on from OSA/SEL/TYO were all available with those connections!

Good Luck and don't give UA money for a W ticket with R == 0 if you really can avoid it! Their C cabins barely warrant W ticket prices.

-jeremy