You've highlighted one of the things I love most about CO. Rare is the occasion when you'll see a non-rev in FC. CO has clear rules about this; Priorities go first, followed by Platinum, then Gold, then Silver, then mileage certificates, then non-revs. The Priority upgrades are usually comps for bumping, that sort of thing.

The thing you should notice from that list is it's based entirely on where the money is. If you inconvenience a paying customer, the Pri upgrade is just compensation. Then you go by loyalty...the goal is to ensure that revenue pax continue to be revenue pax.

I'm baffled by the UA/DL company policies of filling FC with non-revs.