Here is what I do, I used to think just like the OP...I wanted my phone off.
-I go to silent mode at night
-I then plug my phone in to the charger and hit the power button to make it sleep
By doing this, you get the black screen you want and it charges with no noises.
Hope this helps.
it seems like less wear and tear if they are off. My guitar tech says that as long as electricity is running through something, a transformer for example, there is wear.