Overarching Floor Lamp - Polished Nickel $299.00 (60"w x 19"d x 77"h) - You could do one of these, but they are dominant in the room!!! Very dominant. I would do this in the version where you don't have a table with a lamp in front of the bay window.
West Elm Linen-Shade Overarching Floor Lamp, $249 via WestElm.Com --- I love this kind of look in a lamp. It adds drama in addition to being functional. And this particular model is a riff on a retro classic!