Let me preface this... I have limited experience with models, even more limited access to proper equipment (2 umbrellas and Vivitar 283 and 285 for lighting) plus, I haven't had the nerve to post for critique yet, so take this with a grain... make that a lick of salt...
Photo 1: This is my favorite photo. I think the hair light would have been more effective if it had been placed higher, providing better separation on the top of her head. I'm not sure what look she was going for, but the expression on her mouth is confusing.
Photo 2: Her eyes are closed, but it looks like fun.
Photo 3: It doesn't quite work for me. I think a higher angle and the model turned a 1/4 turn more toward the camera.
Photo 4: This is a well excuted photograph. You know your studio photography. My only concern is the model's pose.
Again, these are just opinions, mine and I've told you what they're worth.