Painting different walls different shades of a color

[lbaccar23]

I am looking for suggestions on how to paint a room with two different shades of a color. I am thinking a blue gray color and a lighter shade of blue gray. I dont know if i should use the dark color on the window wall or oppositea a window and the lighter color vice versa? Any suggestions. I basicallly have a square room with one large window on one side.

______________________________
D | Couch W
I | I
N | N
I | D
N | O
G | W
_______|_______TV_____________