A smile should would go a long way, imo...though 5 & 6 are almost hinting at a smile, the washed out look I am not personally into, the horizon line in 6 is bugging me too.
I will say, the shots are pretty crisp and the poses aren't bad, #4 seems the most eye appealing to me, color wise. It's not washed out, nice dof, and good detail and the shadow on her neck really frames her jawline nicely.
Just my humble $.02.