SFGate

michellelouise22 It's a blank canvas! What color do you love to wear? Ignore trends and use THAT color. It will have sticking power for you.

TanCalGal R the sofas centered with fireplace? Center sofas and buy a coffee table. Living Room

For pillows, some do the technique 2-2-1 (see photo) the "one" being the smaller center pillow. Choose colors that are in rug. Is the rug plum? Maybe a plum throw, too. I like simple and often do just the "one" in the center. Pulp Design Studios

I would not paint the back of bookcases. Instead, add a few more decorative items (wicker basket, accent (plum?) colored pottery etc Lorraine Vale

Here's an ideabook on arranging shelves Ideabook: How to Arrange Shelves with Style

mmhicks Awesome thoughts, ideas!! The rug is a brown dash and Albert, but it does seem to have some plum undertones.

mmhicks Oh and sofas are centered it just doesn't appear that way from the pic:)

Jayme Hobbs Thinking I wouldn't paint the backs of the shelves. Pull shades from rug for pillows or a color that ties in with the rug. Nice room!

TanCalGal If you like the look of back of bookcase painted, paint foam board instead...

Harrut Hi,
I came across this picture from the Houzz collection:-
Just a thought !

Carolyn Albert-Kincl Design Here are some pillow possibilities for you, pictured below. To determine what size coffee table you need, measure the space between the two sofas and subtract 36" because typically we place a coffee table 18" out from the front of the sofa. Fortunately you have some flexibility in how close you place the sofas to each other, so that will make finding the right size table easier on you.
Carolyn Albert-Kincl, ASID

A. Peltier Interiors Yes, start with colors you love. Maybe look at your closet and see what color pops up most. Also consider what is your favorite season. You have the brown/plum rug as a start and other than that you really have a neutral palette to work with. For pillows, check out your Etsy, they have some amazing ready made pillows in designer fabrics for a great prices. Then use a down fill with them to get a really rich look. I happen to like painting or even wallpapering the backs of bookcases. Really you have to determine how much pattern you want your room to have. You do need to add a coffee table. If you have kids a leather or upholstered one can be great If you do upholstery, make sure you go for a stylish frame but a durable fabric. That should be a good start, although your room can hold so much more. Good luck, your off to a great start!