if leaving it on all night is such a bad idea, then why is this site always on 24/7?
funadvise is ran by a computer no better than probably a desktop computer. you may leave it on, it wont hurt your computer, however it may waste electricity and hurt your wallet.
id say hibernate would be your best choice because it stores your current state, and later revives it when turning on.
I prefer to turn my computer off after i'm finished using it for the day. i'll leave it on until i go to bed. it saves electricity during the night. if you leave your computer on all the time, you run the chance of overheating it and blowing a fuse or something (plus turning it off saves money)
It's all up to you, but i think leaving it on is a waste of money and as far as i know it can hurt your computer.
Best of luck!