I am flying in early November CPH-ORD, and my minimum bid is also $800 with a near empty plane according to EF. I think there are a total of fifteen seats booked in total right now.

Does the minimum bid drop nearer to departure?

You can apply SK ff number while you bid, and until the check in time (by which time the bid should be either accepted or not), and switch to your UA ff number at check in (or right after).

Got it, thanks.

Not necessarily. The low minimums that I and others received (SEK 2700 in my case) were during peak summer season. I am guessing that economy was way oversold when I bought my tickets slightly more than a week in advance in July. (I bought Plus, BTW.) Historically, they would be making operational upgrades, so they lower the bar for selling an upgrade.They need to move the eco pax up to Plus and Plus into business. Back in 2019 I recall that I paid just above the minimum in the high SEK 7000 range for LAX-CPH, so the minimum was around $800 like now. This was for low season in late Nov early Dec. In any case, the minimum seems tb be slightly lower if you bid in SEK!

To follow up - I checked the minimum bid amounts for SFO-CPH in early October and CPH-SFO in mid-October and they both have dropped to $300 to go from Plus to Business. The Plus cabin looks to be almost pretty full in both directions, but not sure what Y looks like. Based on what I can see through my corporate travel website, SFO-CPH is looking very empty while on CPH-SFO is about 40%, but this probably does not capture those who have not selected seats yet.

As another data point, my friend just flew CPH-LAX two days ago and successfully upgraded from Y to J with the minimum bid of 420 euros. He said Y was about 75% full; I'm not sure what class economy ticket he bought.

Interesting. Maybe they are dropping the minimum based on some algorithm while 3-4 years ago it was pretty firm around SEK 7000 or $800. BTW, it's a bit confusing when you use Y (where I think you mean basic economy or Go) because Y is the (highest) booking class for Plus. In SAS/ LH / Amadeus parlance, economy (or Go) is referred to as M class.

Might be, and I hope it is the case, but I have a trip from OSL to EWR in early November and minimum sits firmly on 7800NOK / 29.000 points from Plus to Biz.

I think wait until early September to see if it drops. Again, the trend in my case has been: 800 USD when more than 2 months before departure, 500 USD when just under 2 months, and now 300 USD shortly over a month before departure. Of course, YMMV.

Any data points on how points vs cash bids are prioritized?

~27k from Plus to Business declined for ewr/osl today :(

What was the minimum when you placed the bid? And any idea of the load in the cabin?

22k or $300 min bid
It went out full, somewhere between 3-6 seats available day of before bidding closed.

Just another data point - ORD-CPH for late September showed up at $500 USD minimum for Plus -> Business when I booked/bid in June. Minimum bid is down to $300 now. I will be adjusting my bid accordingly.

Last min booking in a few days time in Plus has SEK 2700 upgrade as does wide open flight in late October. So my theories are probably incorrect and SEK 2700 is it.

Adding another data point for reference. Flying ORD-ARN in late November, 54 days out the minimum bid to go from Plus to Business is $300 USD (previously was $800). Seat map shows only 3 seats sold so I'm optimistic. Bid a little bit higher than the minimum for two seats and will report back.