I always keep mine running and only turn it off if am going to be gone for a long time, aside from updates and stuff like that requires rebooting. I have found to have more problems with turning the computer on and back on again then letting it run.
I have that thought, lets turn it off for the night to save some power and let it cool down for abit, turn it on in the morning and have problem after problem. So, the saying if it's not broken, don't fix it really works for me.
The sound of the fans isn't as bad as it used to be, can sleep okay.
I would use Sleep mode but for some reason my PC just just reboots from it or it won't wake up from it, I think it's something to do with the USB Hub in the PSU.