I made a topic about battery power as well, this may be helpful.

http://androidforums.com/android-lounge/80417-new-android-user-help-please-battery.html

I leave it charging at night, but that isn't good for the battery's health.

 

Honestly I would say that is a matter of preference. If you don't worry about getting calls or anything in the middle of the night then by all means turn it off if you like. I leave mine on (well I have the Incredible but honestly that doesn't matter lol) since I might receive a call and I also use it as my alarm. If you want to conserve power you can toggle off things that are updating while you sleep.

Hope that helped some.