A couple of winners from the previous contest came back and couldn’t use their upgrades from Michael and now reader Joe has volunteered a couple of more. They expire and must be flown (not just booked) by 31 Jan. More importantly, they can only be used on a W fare or higher.
There are also some other ways to use them, like on Lufthansa, so refer to United’s webpage on upgrades if you have specific questions. So any takers out there? Reply with a comment to this post.