my last 2 operational upgrades on international (both were transatlantic) UA flights were in 1999 (I was 1K then too) one was from eco to bus at check-in time without me requesting anything/anytime at the gate (IAD-ZRH a routeing abandoned by UA since) and the other one was from bus to first (DUS-ORD) again without me requesting it, and it was done after check-in, by a public call for me to the Düsseldorf Senator lounge. The check-in agent beforehand asked me, without mentioning the upgrade possibility, if I was going to that lounge).

But then, there were no SWU upgrades given yet, and I wasn't as rich in miles on my account, and I took the risk to be stuck in coach - which now I don't take anymore for longhaule segments.