I'm not particularly, uh, well-padded but I've found actually that a slightly smaller guitar better accomodates female anatomy (I often use my mothers' Guild F-30, which is just a bit smaller and curvier than a dreadnought). That said, I've come to the conclusion that guitars were not designed for women. Mine tends to either squash things or, if I'm wearing one, causes my underwire to bite me.

I don't know if that helps--I never play sitting down.