Don't paint the wall! White walls showcase art the best. I'd put one large piece of art behind the sofa with some reds, grays, blacks and whites in, and maybe golden greens.

I own this rug from Room and Board and love it:

http://www.roomandboard.com/rnb/product/clearance/detail.do?articleNumber=746662&category=clr_rugs&subcategory=view_all

I think it would look great in your room. Good luck.

Oh, and pull the sofa a bit away from the wall to leave it some breathing space.

You currently have 4 colors in the room:

The floors and shelves are dark brown
The sofa is dark grey
The walls are white and the rug is beige.

If you're going to replace the rug and wall color - What colors do you like and will work with brown and dark grey?

Teal? Red? White? Gold? Navy?

Choose 2-3 more colors that you're going to repeat and spread liberally throughout the room - and repeat the dark grey somewhere as well.

Who makes those shelves? They are great!

"Who makes those shelves? They are great!"

Nobody anymore - They're vintage.
I believe these might be the Cado system.

http://www.poleshelving.com/2007/10/30/cado-modular-shelving-system-by-poul-cadovius/

Why not find a designer (or talented student) to give a proper consultation? Commenters here cannot see the rest of the room nor the rest of the living space, and we have no idea what your use or goals for the room will be. Cream shag rugs and grey walls seem to be default settings for unimaginative trendy interiors right now -- bring in some creativity and personality.

I cool alternative to art could be wall decals, they are less expensive. I like this site because they are easy to put on and reusable.

http://www.roommatespeelandstick.com/deco-wall-decals.aspx

There are other sites with more variety too.

I'd use an off-white or other light color rug big enough to be a little bit under the couch and to contrast with it. And I wouldn't paint the wall, I think white walls are great because you can easily change a room's color only changing cushions and other cheaper decorative items (like some you may put on those terrific shelves). As for the art, I think it depends on your taste... I prefer a grid of framed prints. One big piece of art would call too much attention, and I think your shelves may be the stars of your room.

It's hard to go wrong with a Persian. I would pick one with some colors that you like and repeat in throws and pillows (which can be in textured solids--easy to find). It would also complement any large abstract artwork you might hang above the sofa. I don't think you need to paint the walls.

Thoughts on a collection of art in a non-grid pattern? Asymmetry can be refreshing...

http://s6.photobucket.com/albums/y248/xkwizzit/?action=view&current=livingroom1.jpg

amed must be new to this site!

find artwork that you LOVE, and then choose paint and rug colors that you LOVE... all the better if they contrast

I think we have the same sofa (Jackson from R&B?). We bought the "Par shag rug" from CB2 - it really adds color and is an different approach to the standard shag rug. We also hung a colorful painting behind the sofa. The grey sofa and white walls make the colors pop.

If you go grey go deep deep dark grey and paint the entire room, leave the ceiling white, if you don't go intense the sofa will get washed out.

Look at this room, BM Wolf Grey-
http://gallery.apartmenttherapy.com/photo/070109jonrohousetour/item/54884

Really you could go with so many colors. I would get a rug you love and art you love them decide what color to paint.

that sofa looks like the ikea karlstad to me

Alright - my 2 cents:

1. Light gray sounds lovely for painting the back wall.
2. I think a grid of art would look too busy with your open shelving. Opt for a big a** piece, or 2-3 large pieces to fill the space - with lots of color.
3. A shag rug would be yumm, but maybe in a shade of gray instead of off-white? I am not a fan of mixing white (the rest of your walls) with off-white, but that is probably just me.

Good Luck!

Love the shelving system. What a CL treasure.

Pull the couch out from the wall just a bit as previously mentioned, I would get a print that means something to you or a vintage treasure at a thrift or antique store and then base what color rug you get from colors in the print.

Carpet tiles like, http://www.cb2.com/family.aspx?c=170&f=5881, would allow you to add many different color options for accessories and lay them out anyway you like.

I'd go with a slightly burnt orange, green and turquoise. Or maybe red, orange and pink. Or grass green, goldenrod and white as accent colors. Depending on your style of course. There are so many possibilities.
Also, you should consider choosing a bold painting or some other piece of art to hang over the sofa and use the dominant colors in the piece throughout the room in decorative vases, other framed art and so on.
The colors in this room right now are equivalent to a blank canvas. Which is why have so many options. Just be sure that you can recognize the end result as "you".

Start with the rug! It all builds from the floor....UP! Now may be a good time to admit I design rugs and am pretty much a "rug nerd"....still, even a COUCH person would back me up on this!

Shag seems to be FUEGO and it IS a cool look when it's right but so many shags out there are about as well made as this ROLEX I bought on Canal; it sure LOOKS cool for the first few wears but after that.....you get where I'm going with this....try to buy NATURAL FIBERS like silk or wool before synthetics....rugs shouldn't be disposable.

http://www.halvai.com

Yeah, do start with the rug. It will make a big difference when you get around to choosing paint. (Dash & Albert is my favorite for rugs but they're kind of expensive; Overstock, thrift stores, and obviously Craigslist are other awesome resources).

You don't HAVE to paint; white looks good in your space. However, I would disagree with see's comment that white showcases art best. It's all relative to your individual situation and you may have to find your wall candy before choosing paint colors, as well.

I agree that one large piece will work best to keep the space serene, especially if you plan to fill up those beautiful bookshelves.

TOTALLY agree about starting with a rug and building up. Rug is hardest to find. Once rug is set, find art to pick up colors, and add same colors around the room. No accent wall behind sofa. But what about lighting for this sofa? Maybe a pair of arcing task lights, mounted on the shelves? If the sofa can come off the wall, maybe a NARROW table behind it could have two fun lamps...repeating rug colors again. Would also give you more display space...

There are a few birds on the shelves so I'm thinking a large poster of the sky would make them feel right at home and with a large poster you may not need to paint. If you do, I would go with a dark grey to blend with the sofa. A shag is just what you need with those fifties style shelves. Contrasting cushions, in lime green, white, orange or cream would bring a little zing to your nice sofa.

"Light gray sounds lovely for painting the back wall."

Accent walls are so tired...
...and I always wonder: Why are they so often done on the wall behind the sofa or bed where you can't see it when you're seated in the room?

One large art piece a must with the shelves.

I pulled my sectional off the wall 6-10 inches and used a couple cheap up lights on dimmers; makes the sofa look very sophisticated custom lighting is installed.

By the way, I had to reupholster in a taupe...long story...and the choice of a rug has been maddening. I'm leaning to a deep black, but cannot find a quality one yet (and that fits a budget). I hang a lot of art and really wish AT would do a story on this very problem.

I'd love to do white, but wonder how long that would stay clean...

If you wear shoes indoors I'd advice against white or shag for that matter.