One option is to replace the lamps with two new ones that are taller......I would use lamps that are made from tall oriental vases....perhaps with the shade and the vases, the lamps could be approximately 36" tall.

Another option is to place two thin and tall paintings above each chest. The painting would have similar themes but would be different. They might be just a bit narrower then the chest and almost as tall as the window.......If you use paintings, then I would remove the lamps...

Arrangements of 5x7, 4x6, and 8x10 family photos? At least on one side? Or photos of places you've traveled, or places you would like to go one day? I'm not much for total symmetry myself, so I would do something even slightly different on either side of the window.

If you decide to do mirrors ,they should probably be the same ...you can raise the lamps up with some nice large books or decorative box of some kind