I don’t know if this defines me as a liberal, but my response to 9-11 was not anger. It was sorrow.
Several years ago, a writer named Charles Taylor had a piece (in Salon, I think) about his own response to 9-11. He was angry, to put it mildly. He described, in no ambiguous terms, what he would like to have done to the hijackers. When I posted a comment saying I felt enormous sorrow over the atrocities committed–over the realization that a group of extremists could hate America so much that they would give up their lives to destroy us, and that our country would almost certainly engage in one or more wars in retaliation–Mr. Taylor questioned the legitimacy of my un-angry reaction.
What made me think of this now is a recent conversation about a different subject: the savage rapes and murders of a family in Cheshire, Connecticut. As I read the proclamations by angry people who described, much as Charles Taylor had done years ago, their own fantasies about punishing/torturing the perpetrators of the Cheshire crimes, it occurred to me that, once again, I was way out of the mainstream in my profoundly sad, but not angry, reaction to that horror.
Last Liberal Stand 
My company was the largest tenant of the Trade Center. If not for cancelling a business trip from my home in Seattle to NYC the Friday before the 11th I would have been there on the 69th floor of Two World Trade.
I remember quite clearly I was on the phone with my father that morning. My initial reaction was disbelief and then great concern for the people I knew and worked with. Then I remember saying “It doesn’t make sense. Don’t they know we’ll bomb them off the face of the planet?” and my dad replied “that may be just what they want”.