Here is another shot, this one from the 29th floor of the Sheraton.
You can just bearly see the Cityscape crane right between the Compass Room restaurant atop the Hyatt and the Phelps Dodge tower. With the Cityscape office tower being roughly the same height as Two Renaissance Square, that should give you an idea of how tall it will look.
Between OCPE, 44 Monroe, and the Cityscape office tower, this view is quite a bit different then it would have been just a couple years ago.