If you have the room, I would try moving the sofa off the wall, enough to have walking room behind it. Having it pushed against the wall makes it look like it's too large for the room (and perhaps it is).

Here is another earlier photo I found. Unfortunately this is the couch we had when we moved would like to upgrade eventually but trying to make it for work now.

I like big comfy couches : ) If you can float yours even a foot or so away from the walls, you'd be able to put an arc lamp behind it in the corner and even have room for full length curtain panels on the Windows to add some color and pattern to the room. Don't forget an area rug, I think a light-ish neutral shag would complement the style and color of your sectional and maybe a lucite coffee table to balance out the visually heavy sofa and fireplace.