I'd like to notice (and have others notice) a nicely tailored suit.... and I feel that is when it's buttoned up. However, there is a side of me that feels the buttoning of a jacket is a little over-the-top and screams 'narcissist'.
^ I like that.
I do this purely out of habit (no idea why or where the habit was formed) - when ever I am standing or moving my jacket remains buttoned, when seated I unbutton. When seated, should the need to stand arise, no matter how short the amount of time or the reason (i.e.- shaking hands, woman leaves the table, etc.,) I automatically button back up.