I would try either a black or clear glass oval coffee table with a fluffy rug underneath

http://houzz.com/photos/817655

I'd stay away from any more wood colors, maybe a couple of these drum type sides.

http://houzz.com/photos/103538

Oh, and for the corner in your second picture, maybe a plant? A basket of books or magazines?

Restyle your shelves. Move the taller heavier looking volumes to the bottom shelf and add large shallow rectangular baskets on the floor under each section to anchor and visually reduce the inherent flimsy appearance these kinds of shelves have. Baskets would also add some much needed texture. Shelves would look much better with 1/3 books, 1/3 decor items and 1/3 open space. Books can lie on their sides too. You could use a great area rug to add color and pattern to the space. Center it and move your furniture to it for a more conversational grouping. The art collage is mounted too high on the wall and is not exactly what you need here. They might work well going up the stairs. I'd suggest replacing it with some colorful contemporary art that is quite large. A credenza under it would look nice A glass and metal coffee table would bring a bit of sparkle in. Go for a round one to pick up on the arches in your room. Everything is very square and rectangular so try to break out of that monotony with some shapely items.

this wood table lamp.How about?

Decoenthusiaste, thanks for the very thoughtful comments and product suggestions.

Hope some of them work for you, bottlegenie!