Originally Posted by
MSPeconomist
Sometimes you get lucky and find an international aircraft on a domestic route, such as the 777 between ATL and LAX, but these are rare and special circumstances and unlikely to apply to the OP's AUS to SEA/GEG route.
Perhaps it's hit-and-miss at DL, I dunno, but AA has regularly scheduled 763s between DFW and LAX, but only 1 or 2 in the morning. They may still have those slightly angled flat seats up front (their "Next Generation Business Class" seats from about a decade ago), I'm not sure if they've all been updated (to truly-horizontal lie flat) or not, but that's still tons better than the conventional domestic first class seat.