I guess the fact that, during oral, it provides enough room for my gf to use two hands and her mouth. I love everything about that feeling, and how it looks. And the benefits of the thickness: it makes my penis look really "muscular," and my gf loves the stretched feeling.
Otherwise I don't think about it much, especially not during the course of my day. And while my gf appreciates the development, she still loved my cock back when it was only 5.5". And I never really had insecurity issues anyway back when I thought it was smaller than average (though I realize now I was always at least average).
But honestly it's not that different, especially for someone in a committed monogomous relationship. Maybe others notice a pants outline occasionally; I really don't know and don't particarly care. If you're small you're not missiing much.