Depending on whether or not noise coming through that window is a problem, you might want to consider interior shutters.
Basically, the more mass you can put over that window opening, the more noise you can stop from getting into your house through that window opening. 2 or 3 panes of 6 mil glass just plain doesn't go very far when it comes to keeping noise out. A pair of one inch thick laser engraved hardwood shutters would be very much more effective in that department.
(Keep that in mind for bedroom window treatments, maybe.)