I would switch it of...
...but I want them to clean-up, de-frag, re-optimise the virtual images and do some other housekeeping after I am gone on a Friday. So I automated all that via Windows Scheduled Tasks. I have yet to find a way to issue a "Hibernate" command from such a thing.
The whole "power down if nothing has happened in 30 mins" is bullshit as something IS happening, but it is not user input.
At home I would like my PC to do some housekeeping (e.g. AV scans) during the night. This would mean bringing the PC out of stand-by and sending it back again, BUT also co-operating with other programs. i.e. do not send the PC back to stand-by if Media Center is recording.
There also does not seem to be anyway to tell Media Center to send the PC to stand-by after it is done (and not other program is running a housekeeping task of course). All you have is the shitty (and useless) "go to sleep after 30 mins" which is annoying if you are watching a movie!
At home I use "Stand-by" as I am not sure if the PC can be woken from "Hibernate" by a scheduled event. As I have said, I know of no clean way to send it back into "stand-by"/"hibernate" once the job is done.
So do not blame the users for the failure of the OS/applications to make such things easy. I have no idea if it is a similar situation with Linux.
You also have to consider the wear-and-tear on systems of coming up and down. How much of that £300 million/carbon-footprint be eaten into by failed drives etc?
I do, however, power off and unplug everything I can when it is not in use, even though my employer does not give two damns due to how we are metered.