I would recommend rebuilding, but it will be a tough sell getting anyone to work there. I will predict, however, that it will not happen, at least not on that scale. Probably 1 tower about the size of the World financial center.

We must find a way to protect these buildings, as the empire state building, sears tower and others could be targets. Phalanx would probably be too close in, We need stingers, or something that could react quickly.

Also we need a better way to fight fires and support damaged buildings. possibly halon + large halon airbags on every floor. That way the air pressure would support the damaged structure. This would be useful in earthquake prone areas also. I was amazed and proud how long those giants stood.

Unity against terror! Long live the United States.