What a neat opportunity! I absolutely love that second shot. Wonderful perspective and DOF--I love how you can make out the woman peeking over at you in the background. It draws me in and keeps me there for a while. Nicely done.
It reminds me of a quotation I read at some point, which I will have to paraphrase now, something like:
Photography is all about what is in focus and what is out of focus.
On the third shot, I like how the main figure has no head, but Bill's head floats on the book -- you have a bit of a sense of humour, I see...
In your last shot, I want to crop off most of the people on the far left because they don't seem to add anything, imo. Maybe even as tight as the left side of the man with the black and gray logo jacket. To my eye, that places a little more focus on the lady in red turning towards you and the sign.
I am curious as to the expressions in the Secret Service guys eyes as they look not at Clinton, but at the crowd.
My eyes are more drawn to them, than to Bill himself.
Great shots, its about more than just the main person, but about the event as well.
That last one made me laugh out loud.