Thank you all for the information. That is very helpful! Seems like it’s well worth checking every now and then to see if those Z class fares are available on our booked flights, as it sounds like they might not bother to upgrade us unless I prompt them to. Then by the time 24 hours prior rolls around, they may have sold all the inventory for a cheap price.

i did find one day that had a Z fare from SEA-AMS, but when I changed it to SEA-AMS-NBO using the same SEA-AMS leg, the fare class changed for that flight. They sure don’t make it easy.