My recommendation would be a rectangular metal finish coffee table with glass top. You don't have a very large space and your sectional is fairly heavy so a see thru coffee table would counterbalance the room.
http://houzz.com/photos/7082208

The area rug is an 8x10 to give an idea of the size.

I like this one. $220

http://www.wayfair.com/Monarch-Specialties-Inc.-Coffee-Table-I-7890C-MNQ2066.html

I agree with Vickie Daeley, looks as if a round would add a nice shape with the straight clean lines you already have. Is it possible to switch the chair and the sofa? It might open up the window a little. Also as you can, add side tables and even a sofa table, and on these tables add lamps for that good lighting opposed to the harshness of a ceiling fixture.
Oh by the way who is that big guy or gal with all the wrinkles, I had a big gal, named Sammie. How sweet are they????

Thanks everyone for your comments. I thought about switching the couch and chair where the chair is leads into the dinning room. Didn't want to post a pic as we have to figure out what to do with the old live seat and coffee table which is in there. This is a different layout than what we before but hubby really wanted sectional and man chair. The living room is about 13 feet. By 13 feet. Here is the view to the dining.

Also am thinking if I should lighten the curtains to a light mustard or something

I had an arrangement much like yours. I went to Norwalk furniture and had them build me w custom ottoman that was several fabrics and the ID coordinated it with my colors. I would also concur that glass would be a great choice because it would open up your room.

We had the same situation, didn't want a heavy table in a small space.
We opted for carerra marble top (on teak) rather than a glass top.

If you switch the sofa and chair, it looks as if it would be a nice look with a sofa table ( very narrow ) on the entry space, with a lamp and a spot to drop keys etc. then with the chair on window wall with a table and maybe even a small side chair close to the white bookcase. I do think your thinking great with the mustard color panels and then pick that color up in your sofa throw pillows. You also could have room for a small side chair at the foot of the sofa. The side chairs could be used in the DR as you have need of extra seating. Good luck it is shaping up quite nicely.

Love the rug where did you purchase it?

Since hubby has his man chair, consider adding something more feminine with the sectional. I'd try a pair of ceramic garden stools, perhaps in turquoise, mustard, or even a metallic to add a bit of bling.

Rug is from pottery barn. :). Actually so is the couch and chair we had to order the furniture but the rug was in stock.

Oh and that's Rocky is the pic! Someone asked, he is the best!

Okay I found this one and I do like it. It's a small square. Reclaimed wood from fishing boats with glass in the center which makes it a bit "lighter." I love the Reds yellows and one strip of blue.

Maybe I should change the curtains now..,,,