Originally Posted by
MSPeconomist
Correction to the OP: DL DMs and PMs do *not* get last seat availability for instant upgrades to C+ even on domestic routes. DL C+ "upgrades" are inventory controlled, although these supposed "upgrades" can be confirmed at the time of ticket purchase by DMs and PMs not on basic economy fares if the appropriate inventory bucket is available.
I'm not aware of any reports of SU<W on the DL forum that exceed the background rate of weird computer glitches, but if I'm missing something please let me know. I know DL does not advertise last-seat, but IME so far it has been for all practical purposes