I hope its OK to give my personal thoughts.
My eye initially goes to the main subject "first" in a image, especially where an environmental portrait is concerned, so if I compare the first two posted images, I prefer the 2nd one. Not because the view through the windows has more detail of the buildings which sometimes can be a distraction, but you subject (your friend) on my monitor looks slightly better lit. I do wish though a small bit of "fill" or modeling lighting was added to her pose.
For the 3rd image, I would maybe apply a little post processing to the bridge of her nose and also just slightly to her cheek to smooth things out a bit (may be nitpicking), but really like this one.
The forth image is nice too but I personally think her eyes/gaze didn't work as well as it could and if her gaze was slightly altered/different, it would have made a big difference. Again these are simply my preferences and I can respect those who specialize in portraits and could certainly add more than I could.
Once again a lovely set of images in a very nice location!
Dave (D&A)