For United, this is their
Introducing Nagoya, Japan promotion, which as UnitedSkies pointed out, is part of their inaugural service from SFO-NGO (with the aircraft continuing on to TPE) beginning on March 26.
Plus, Mileage Plus members can earn
double miles between the San Francisco - Nagoya route (valid only on flights 830/831; specifically San Francisco and Nagoya, Nagoya and Tapei, San Francisco - Nagoya - Taipei) ^
My wife and I will be onboard, from IAD-SFO-NGO-SFO-IAD, departing 3/30 and returning 4/6.
When we initially did the reservations, the fare was around $629.xx (total), then it went up to $650.xx, then dropped a few dollars, and by the time we finally ticketed it (we had some discount certs that we applied), the total was $659.17. Within a week, it dropped to $629.06 and this morning, it was $554.06. When I called United by late morning to reprice, it was $529.06!