Any suggestions? This is Safari 6.2.7 on a 2009 MacBookPro using OS 10.8.5
I am the same version of Safari and OS as you, except my machine is an older Intel iMac.
The last while, maybe a couple of weeks, Safari has occasionally unexpectedly quit, although I am not certain that it would be every day. My routine is a bit different from yours. I do not leave my machine on all night - I log out, put the machine in sleep mode, and log in.
However, for the 'unexpectedly quit' events I recall the dialogue box had an odd message. It was something like "Safari content
has unexpectedly….". Do you get a message like that?