Denim jackets
I only ever wear my denim with nothing else underneath, so I guess the questions relating to shirt buttons don't really apply. Some of my pals wear theirs with a t-shirt, or a singlet, but I like the feel of the denim on my back. Still, each to their own, I guess.
being a girl, wearing my denim jacket with nothing underneath isn't much of an option LOL. but I love my levis jacket and now that the weather is getting colder I get to wear it more often!
I've been giving this some thought, and what I'd suggest is that, next summer, just wear your denim with a bikini top underneath. Hope this has been useful, and post back here with what you think.