I would address the wall with a collection of some sort that mimics the lines of the ceiling, or add a dynamic piece of artwork, clock etc..

Take a look at these idea books for large wall displays, I think they may give you some ideas:

http://www.houzz.com/ideabooks/query/large%20fireplace%20wall

I would suggest you place a huge mirror above/on-top of the fireplace and have it leaving slightly on that wall. Then place some nice pieces that you like such as vases etc. in front of that to add some dimension and depth.

I don't think that it's the lack of something above the mantel that's not bringing your space together - You have a Mansion-sized space in a rich, dramatic color that's filled w/ apartment-scaled furniture and summer cottage-style bookcases & slipcovered sofa.

I'd replace those white cottage bookcases with a pair of sophisticated 7' tall brass Etageres such as these from Worlds Away: http://worlds-away.com/product/etagere-gold-leaf-w-clear-glass-shelves
or this one from Billy Baldwin:
http://www.ventryltd.com/products_pg_images/bb_porteretagere1.pdf
...and replace those empty frames & small little items with large ceramic vases, stacks of coffee table books, large lacquered decorative boxes, heavy bronze bookends, etc.

Then at the windows, you need some dramatic floor-to-ceiling silk or velvet drapery panels hung on a chunky wooden rod...
...and those iron tables need to be replaced w/ some chunky, carved wooden tables - Something with weight and substance...
...and big chunky ceramic table lamps with oversized shades would be much better than that petite crystal lamp which you can hardly see.
Finally, a pair of fully-upholstered armchairs would suit the scale of the room much better than the open chairs...
...and a new slipcover for your sofa in a richer fabric - perhaps a velvet, damask or chenille with some silk or even fur throw pillows.

I'd also rearrange so that the back of the sofa is to the windows, and the chairs are facing the sofa from across your big square wood coffee table

Once you have the basics in a scale that's appropriate to your room - along with a nice large, plush area rug layered over the wall-to-wall to anchor the room - you may find a nice big round mirror in a chunky carved wooden frame or a beautiful large oil painting in an ornate gilt frame will be the perfect thing for above your fireplace.

I would have a cabinet maker build a large overmantle! I had this situation in my previous home and the installation of an overmantle was just the balance my wall needed. Good luck!

the karrot457-I like that idea. Friends of ours who used the same builder did an overmantle. The only thing they said that they didn't like about it was that it limited their options a bit as far as what to put over the mantle.

Hello, I like your look. I would move the book cases to a dirrerent room. Move the two chairs (They are really nice) to eighter side of the fireplace. Don't use any curtains..unless you need the windows covered. I do believe a great mirror above the fireplace will jazz up the the area. No need to break the bank in pulling this area together. Good Luck

I love the chairs! I agree with csh0914.....put them in front of the fireplace. I also agree with a chunky wood coffee table. I know....doesn't really address the fireplace.....

I think a large mirror would look nice. Depending on what it reflects, I'd go with a large simple round one that extends above the bookcases. If it reflects the kitchen area (cabinets, microwave, etc) go for a large, tall one that's rounded (arched) at the top but that you can 'lean' on the fireplace mantel. If it's leaning, you won't necessarily see what is across from it if it's the kitchen.
A designer friend advised me to always be careful where you place a mirror. If you don't like what it reflects, you'll be stuck with double of that view (the actual view itself as well as a reflection of it). In any case, I'd keep it simple and I do feel you need more 'round' in the room to balance it. Hope this helps!

Restoration Hardware has a fantastic selection of round and arched mirrors in many sizes!