Many years ago, when I was 17, I used to leave my guitar out of the case, even when going to bed at night.
At that time it was a Framus 12 string (burnt some years later in a fire at a friend's home).
One night, my father got into my bedroom, didn't see the guitar and it fell down, suffering a huge and bad crack.
Now, every time I stop playing, I clean it a bit and always put it into the case and close it.
About opening, I don't know what the others do. I simply play it, and it becomes a time when you get really familiar with the shape, the frets, the sound, its soul.... So, you make it sound better.
And it's true that the guitar gets more 'full' sound (I don't know how to say it in English). In Spain we use to say that 'the sound gets more body'.
And it only depends on how long you spend playing it.