screen saver vs sleep vs shut down

You can safely put your MBP to sleep at night merely by closing the cover. You won't have a heat problem as once asleep the processor uses very little juice. Open it in the morning and it will resume where you left off. I seldom turn my PB off, usually just do a restart if I have to for software updates or once every couple of months to let the battery drain and recalibrate.

There is no value in just letting it go into screen saver, you don't save all that much power and don't gain all that much time to restart. Put it to sleep.

One suggestion would be to purchase a laptop stand with an integral cooling fan, usually under $50, and leave it on at night. Also, don't place your laptop near the discharge of an AC vent to keep the dust contamination down. Keep a can of compressed air handy for stubborn dust but be careful with it. Its use can facilitate moisture buildup from condensation. I use a USED Shaving Brush to clean off my keyboards and displays. Its bristles gets very soft with use and works really well. Be careful here as well because you don't want to brush any dust into the keyboard. I typically hold mine upside down to do cleaning.

pw