Wow! What a frustrating and long evening. While delays are par for the course, the screw up with the upgrade would have really cheesed me. You seem to have taken it in good spirits -- better than I would have.

As for the part issue, since AS only has two planes in/out of EWR each day, it wouldn't be cost justified for them to have a full inventory of parts there. Imagine if they did that compounded by MCO, BOS, IAD, DCA, MIA. That said, I would expect them to have a comprehensive parts sharing agreement with all of their code share and/or Frequent Flyer partners. Given this includes AA, DL, NW and CO I would think that finding a part for a 737 would not be too challenging. Esp. since EWR is a CO hub. Why AA wouldn't give the part up when a replacement was on the way with 12 hrs. is a mystery to me.

As for flying or not flying to their East Coast destinations, I would find it impossible (or extremely difficult and certainly less cost effiicient) to earn MVPG without two or three AS transcon flights.