Well, you won't want to visit Chicago at this time of the year. So if anyone's going to make it work as a tourist destination, when snow in April is a reasonably frequent event, it's going to be on the current calendar. For a biz destination, VS needs to sort out how to compete with BA for UK-based passengers, it has no chance with US based ones for many reasons that have already been enumerated.
I did this a few times in the last four years, and it definitely was an underwhelming experience when used to flying out of SF. While that is a tough and unfair comparison in some ways, the check-in experience was regularly poor to fair, the security setup a total nightmare, the lounge worse than a Red Carpet or Admiral's club (and that is saying something). Absolutely no incentive whatsoever to fly VS here unless you happen to fly them regularly to other destinations. It's been said before, that is just not enough.
I slept better in UA's new C seat than I have in the bed I'm currently bunking in [:)]
UA is {more or less) FIFO for clearing upgrades before the flight goes DM. They actually have two FIFO lists, one for GS/1K, one for everyone else. I never had a problem clearing upgrades to LHR even back when I was Premier with them. Two things to note here. It's really FIFO - you add yourself to a list expressing your interest to upgrade, and when it becomes available you get it, in the order you requested it. Not only is this not totally status/fare driven, it actually favors lower status FFs who maybe fly more for leisure, but plan carefully to upgrade. And it avoids you having to check every day whether space has become available. Secondly, with a system like this the ability to set up a list that provides some level of priority to your highest status passengers provides a significant incentive to achieve that status - and we've had many discussions here about 'why be gold'. It's a bit harder to get 1K on UA than gold on VS, but the rewards are meaningful.
Not to even want to start a comparison thread between VS and NA airlines - in many ways they don't compare. But I do think the system for managing upgrades is much better both in how it practically works, and in how it provides some incentive for folks to achieve higher status with the airline.