A large group of us flew from YYZ-SYD on W fares and the transpac segments were upgraded with GPUs at time of booking. The transcon segments however were not except for 3 people who were upgraded shortly after booking. We had some major schedule changes but everyone was in identical fare classes (W) when all was said and done.

Outbound was YYZ-EWR-SFO-SYD.
Return was SYD-IAH-YYZ.

On the EWR-SFO flight, I chose a flight that was an hour later than everyone else as I thought we'd have a better chance of upgrading since all my friends were on the earlier flight. There was just my girlfriend and me on EWR-SFO. She has no status (with any Star Alliance carrier) while I am 1K. I checked in first. When I checked the upgrade list, she was ahead of me on the waitlist. In the end neither of us cleared.

On the IAH-YYZ flight, the entire group was on the same flight and all on W fares, so it was interesting to see their standings on the waitlist:

1) Non-status
2) Non-status (my girlfriend)
3) 1K member
4) 1K member with 2MM LT miles
5) 1K member (me)
6) 1K member with 1MM LT miles
7) Non-status
8) Former Gold member who lost status in Feb 2019

There were a few others but I think they were all non-status. This is all my screenshot would hold.

If I remember the check-in order correctly, it was 4, 7, 8, 5, 2, 6, 3, 1.

Once again, no one cleared, but how does UA prioritize the waitlist???