This interests me, because I am actually working on a few femme!___ right now. The one that I'm putting a lot of time and thought into is my femme!Dr. Crane (Scarecrow) from Batman. I really get annoyed by a lot of what you have been talking about --the girls that basically throw on some underwear, and maybe one distinctive accessory, and call it a cosplay-- and that's why I have always intentionally avoided that. In fact, my Crane was inspired by both old school comics of him (I've been reading Batman for over a decade), with a few touches of the new movie. It's a combination of the scruffy, bedraggled suit, while using accents of his Scarecrow garb (the hat, mask, syringes, etc). It's tailored, of course, to fit my body, but it's not revealing (in fact, less cleavage displayed than on a normal day, for me), and it's true to the character.
I have always wanted to do a crossplay, because I LOVE gender bending, but it's ridiculously hard with my body type, unfortunately. I'm a 36/26/36, and it's extremely painful, if not totally futile, to bind. Because of this, I usually end up feminizing my characters (Jack Sparrow, the Crane I'm working on, the Comedian I'm working on, etc.).