I’m off to Boston first thing Tuesday, flying SEA-DEN-BOS and returning BOS-SFO-SEA on Sunday. From those routings, you can tell it’s United, can’t you? I’ve applied to upgrade both trips; in each case I’m confirmed on one leg, waitlisted on the other. 15K miles for each upgrade; I’m drawing down my MP balance as fast as I can…
UPDATE (onboard at SEA): the upgrade went through, so it’s 1st class for both SEA-DEN and DEN-BOS. This is good, because this flight is 100% full.