A rug of some sort would definitely make the room feel more cozy.

Could you put your bookcases together against the wall where the blue chair is? They are a bit dark and imposing, which isn't bad, but I'd like them together and not as prominently featured as you walk in.

Something lower against those walls: cabinet, console table....nice good sized artwork above it. Or one or more decorative mirrors above one of those items.
How do you feel about a feature wallpaper on the wall behind the sofa?

I see the potential here for FUN! I hope you do too. Your furniture colors are basically sort of primary, fun colors so maybe you could pick up that simple theme and make the room a fun entry/entertaining area away from the family area created by the den. Anchor a conversational space in the center of the room with a very large rug. Pull the furniture closer and onto the rug for a more intimate setting, with coffee and side tables (not matched) but on the fun side. That long wall behind the sofa has great potential for art and/or accent color or fun wallpaper. You might find the rug first, or the art or the wallpaper, but base the room on the concept of a fun introduction to your home and family. To close the room off from the bedroom side of the house, consider the popular "barn door" sliders seen in pic #3 below and move the bookcases to the wall where the blue chair is, painting the back interiors of them or wallpapering them in another fun color or pattern. I'd add a table and chairs in front of the window for casual coffee with a neighbor, a game of cards or Scrabble, working a puzzle - simple activities to give a break from TV and all that.



https://www.houzz.com/magazine/get-more-bang-from-your-bookcase-stsetivw-vs~1428440

Just some examples:

Wonderful window area by the front door. I wonder if you would consider painting your bookcases the same color as the wall and putting them side by side in the room. Is there room on one side of the doorway to the hall? It would be nice to take advantage of those windows and have a seating area there...but facing the sofa to the window with the chairs on either side would still leave half the room empty - unless you put the books shelves where the sofa is now and added a chair and light by them. Or how about this - a chair on each side of the window, the sofa floating in the room, the bookshelves where the sofa currently is - then to get to the hall way - you position the sofa so that one either walks in front of or behind it?

I love your space but can see the awkward arrangement is making it seem unfinished. I would center the sofa on the wall where it is currently then move your two bookcases on either side of it. This will bring some balance. Above the sofa I would add a large art piece then I would add your two existing chairs flanking either side of you sofa. This will give you a U shape conversation area. Add a natural sisal rug bound in black to tie in the bookcases and ground your new seating area. Then you may want to consider adding a round tufted ottoman to serve as your coffee table. Back to the other side of the room by your lovely front entry add a narrow console table on the solid wall where one of your bookcases use to sit. Over this new entry table add a large mirror and perhaps a pair of tall buffet lamps. Last thought would be to add a low profile garden style bench under front window. Good Luck!

I agree with Joy's comments above; I would add some wall lamps to the side of the bookcases on either side of the sofa, would make a great reading area!

Definitely a rug would help.

There are a few directions you could go in for art.

3 pieces of art that are vibrant.
http://angelina-vick.artistwebsites.com/featured/then-the-sky-exploded-6-angelina-vick.html
http://angelina-vick.artistwebsites.com/featured/then-the-sky-exploded-4-angelina-vick.html
http://angelina-vick.artistwebsites.com/featured/then-the-sky-exploded-5-angelina-vick.html

Or 1 wide piece
http://angelina-vick.artistwebsites.com/featured/then-the-sky-exploded-2-angelina-vick.html

Or a continuance of the bold/clean/minimal look
http://angelina-vick.artistwebsites.com/featured/velocity-2-angelina-vick.html
http://angelina-vick.artistwebsites.com/featured/the-hubris-of-mankind-3-angelina-vick.html
http://angelina-vick.artistwebsites.com/featured/flight-pattern-red-angelina-vick.html
http://angelina-vick.artistwebsites.com/featured/the-hubris-of-mankind-1-angelina-vick.html

I can also see this minimalist series serving your space well.
http://angelina-vick.artistwebsites.com/art/all/nonrepresentational+abstract/all?page=2

Thank you Joy!

Thanks for all the suggestions!

I like keeping the bookshelves separated (it makes them too looming otherwise) and we previously had them flanking either side of the sofa. We moved them to surround the doorway because it felt like all the furniture was pushed up against the sofa wall. I like the idea of adding a bench in front of the window, as Joy suggested. I also like the idea of adding extra lighting throughout - this room has NO overhead lighting :(

I've been considering adding a long sofa table behind the sofa to get it floating off the back wall some - like this:
or this: http://www.mangotomato.com/2012/10/diy-sofa-table-project.html

We're also looking at getting a new cover for the green Ikea chair. I'm thinking something like this: http://www.ebay.com/itm/NEW-IKEA-KARLSTAD-Chair-Armchair-Cover-Slipcover-Linneryd-Natural-/251320365665?pt=LH_DefaultDomain_0&hash=item3a83dc7261
Maybe even swapping out the chair legs for something more classic.

Suggestions on rugs? I'm thinking something neutral because of the red & teal furniture I'd like to keep. I'm also thinking yellow accent pillows - yes/no?

For really good Ikea chair covers, look at Bemz. I've heard good things about them and they have fabric options galore.
http://www.bemz.com/en/product-page/product/armchair-covers/id/ekt4/ektorp/

decoenthusiaste has a great idea for your living room It's a young colorful exciting solution..Go for it.

Right... I went a bit mad with possible options, but I really see a colourful, bright and inviting living room:

That striped rug is great!

Forgot to mention that I found everything apart from the chair covers (Bemz) on overstock.com.

Carolins - we're on the same page; this room calls from some color and fun. Love the striped rug you suggested! I think I went off the deep end with my ideas too. Didn't get any response to it so I'm guessing this will end up being a more conventional space than we're envisioning!

Deco, definitely on the same page :-)

Deco - I love your ideas, but I've been trying to pull back from interjecting too much color in this room. Our last house was color, color, color - but this new house has us thinking of ways to keep the red sofa as an accent piece instead.

I'm leaning towards red, teal and yellow as our main accent colors in this room and keeping everything else neutral. Like this: or
And this:

But I'm struggling with how to tie items together and where furniture placement should be so that the house is welcoming when first entering.

Maybe grasscloth in the back of the bookcases to lighten them up?
Something like this:

The little wood chair you see to the left of the sofa I'd like to reupholster in a white linen-type material. Like this:
Or maybe darker like this:

Carolins - thanks for the tip on Bemz. Their fabric options for covers look AMAZING!

Here are some rooms with some those colors. Teal would make a great accent wall.