I wonder that myself sometimes.
What would have happened if we had just kept on going, we had it in the bag, Baghdad was ours, and yet, because of political expediency, we didn't do it.
What would have happened if we had taken out Saddam in the first Gulf war?
Personally, I don't consider the Persian Gulf War to be a different war than the Iraq war. There was no 'peace' during the Clinton Administration. We were bombing them, they were trying to kill us. It was a low-intensity conflict, but whatever it was it wasn't peace.