I'm sorry, I haven't paid much attention to style, and least of all sitting style. Although as a freshman in high school, someone said that a certain sitting style I had looked effeminate. I never sat with one foot on the chair again. Anyway, thanks for including me in this discussion. It would be hard to photograph legs like that in any pose, wearing any clothes (is this prose?), an have them NOT look sexy. So, in a word, Yes!
I'm not a male so not truly qualified to answer this except to say that, if a woman has a great set of gams, no matter how she sits, she will look sexy, unless she weighs 300 lbs.
I love leg display. I do not think crossing your legs is a great idea though. I used to sit like that all through my youth and now I have spider veins where my knees pressed, etc.
We need the circulation. Better to angle them sideways one on top of the other so as not to strangle the veins as much.