Call me a tree-hugger if you must, but I see no reason to keep a computer on when it's not in use. That wastes electricity, which is bad for your pocketbook and bad for the planet. And it's probably bad for the computer.
Yes, I have seen occasional arguments that shutting down a computer, then starting it up cold, cause more wear and tear than leaving it on for 12 hours. I just don't buy them. All computers potentially suffer from heat problems, and one that never gets a chance to cool down will suffer from more of them.
Besides, a computer that's off is a computer that can't be infected with malware or behave under orders from afar if it's already infected.
