Not sure but Ive always been under the impression the order "should" be these days
1. Upgrade 75ks
2 Upgrade Golds
3 Upgrade MVPs
4 Upgrade DL elites
5 Upgrade non elites with cash or miles
6 Upgrade Uniformed Military (unwritten rule and done as courtesy)
and the web is supposedly fixed to keep cash upgrades or MVPs from jumping the que at OLCI with that upgrade this flight button once a flight is under AP control ie the old 24 hour free for all
I was talking to a friend recently and he suggested that buying and using gold guest upgrades will put you at the very top of the waitlist, even before 75ks. I wonder if that's true?