Number 1 seems flawless and is definitely my fav. Well done.
In number 2, I can't help but think it might have looked better if her legs/feet were in focus too. Otherwise, nice shot and great pose.
Now number 3, nice pose and idea, but because she's not positioned exactly in the center of the arch (with the center of her body over the center of the arch), I find it distracting. But I really like the idea. (Y)
In number 4, her facial features appear too soft (other than the eyes, which makes me think they've been sharpened in PP). I would have liked to see her lips and eyebrows a little sharper. It's still a nice shot.
All in all, a nice set - and great ideas with poses and lighting. A few minor adjustments to think about next time, maybe? But hell, I've never used a professional model, so what do I know? Just a little constructive criticism.