So, for priority within a tier -

do we actually know if this is true? They're keeping DL's reservation system, but NW's loyalty database... does the upgrade priority come from the res system or loyalty database? On NW's system, upgrades within a tier (e.g. upgrades within the plat elite tier) were done by "customer value" - basically, how much $$$ the person had spent on 012 tickets. On DL, it was done by fare class (e.g. plat on B trumps plat on M, even if the plat on M has a higher annual spend).

Not sure what the upgrade order is going forward. Personally, I like the idea of annual spend. I might occasionally fly on a sLUT fare for some personal travel, but I would enjoy getting upgraded over a mileage runner who costs the airline money who just happens to be on a mistake B fare.