I think the first one is really well done, other, than as mentioned, her blank expression, but I think it needs a crop off the RH side to knock her out of the middle of the frame. The second would be improved I think, with a tight vertical crop, but again, the expression... .bleah!
On its own I like the first shot. I don't mind that she's centered or that she's posed square to the camera, for the graphical impact of the colors in the shot this works. I do wish there was a bit more light on her, particularly her face, either by a reflector or fill flash.
On its own, the second shot doesn't do much for me. The lighting on her is predominantly too flat, particularly in contrast to the large blown areas on the wall and sky. I don't feel the dead space to the left or the extra headroom add to the shot.
As senior/grad shots I think these fall short for a couple reasons. One is her expression, which has already been addressed. The other is that she is such a small portion of each shot, and what there is of her is largely in flat shadow. The shots don't come across as being about her as much as about the scene. I like the first shot because of the colors, the structure...you could put practically any model in there and the shot would have the same impact on me.
aside from the above comments about expression and composition.... the first shot really bothers me because of the way her legs look. If I were her, and I saw that shot of me, I wouldn't buy it because her knees look lumpy and her legs don't look shapely. If she would have been posed with knees bent it would have improved that shot. Maybe with weight on back leg and front knee bent... I don't know for sure, but that straight leg, locked knees isn't doing it.
See, that's what I get for taking my time typing - you added some shots in the meantime. The smiling shots are a definite improvement.
I still think they are zoomed out a tad more than ideal. I like the symmetry of the shot between the buildings - you'd have to decide if it works for you as a square crop, for instance. And I think that, on the last (leaning on the wall and smiling) if you crop away most of the left and some of the headroom you'd get a tighter, more interesting shot that's clearly about her and her personality.
One thing that stands out to me, is that she takes up such a small percentage of the shots. And although we can't really see her foot/feet where they meet the ground, it's right at the bottom of the frame (or below/cut off)...while at the same time, each shot has plenty of room above her head.
In other words, I think the compositions could be improved by zooming in, getting closer or just cropping.