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.