Your living room is beautiful! It just needs some pops of color. You already noted some good places, in your pillows & window panels. Perhaps a nice deep cherry red for both, or a combination of a few pillow colors with a chocolate brown window panel.
I'd also add larger artwork, perhaps some pointillism or impressionism works, sample below. And how about one or two 6 foot artificial green trees in the corners? I hope I've helped!

The curtains are the main issue I see. I don't particularly care for the way they're hung and they are too transparent. The rod should either be mounted across where the window is divided with the wide trim or at the break where the arched top starts. I'm seeing splotches of red on the rug - are they part of the design? They look so random, I wondered if they were pieces of colored paper just dropped on the rug. If they are part of it that might be your accent color for pillows. You might consider painting the walls a very light version of the gray that seems to be in some of the brick at the FP.

I think more patterned pillows would be good. Here are a few ideas for you:

http://deciture.com/essentials-marine-blue-pillow/

Or

http://deciture.com/ik-ayaka-brown-velvet-on-linen-pillow-w-down-fill/

Or

http://deciture.com/ik-idrissa-embroidered-pillow-w-down-fill/

Hope this helps you!

Love that idea about the pillows thanks! The rug does actually have the rust red in it.

You have a great space! I would look to get some colorful/patterned pillows, I would probably stick with cool colors so they fit with the couch and ottoman, like the pillows on the blue couch below. I like M Rene Designs' idea of replacing the current pictures/paintings with bigger, bolder ones. Then I would decorate your ottoman with a tray, like the photo below. This will add more detail to the room.

Lose the drapes. What is that brick wall--a fireplace? Could you give us more views of the room?

For window treatment, you can enhance the beautiful outdoor view with white verticals which offer an inviting open airy concept where you can manage the natural light emitting in your space as well as privacy. Contemplate introducing accents of salmon/white in solids used interchangeably with patterns of salmon/blue/brown to stimulate interest. Walls will establish cohesiveness and adaptability with these accents when maintained in white.


http://www.pinterest.com/lifespaceintl/lifespace-month-of-july-design-offering-board-virt/

Curtains gone, art lowered, brighter pillows to pick up the colors in the rug, brighter lamp to echo the ottoman. When you have a view like that, it deserves to be showcased.

Good Lord Groveraxle I love those pillows!!! where are they from? Looks pottery barn! And is that lamp from Target ( well at least they have one similiar!)

Here are some more pictures of the room as requested

I feel like the room needs some color. How about a large piece of colorful artwork on the brick wall above the fireplace? Currently, it reads very cream/brown. Will you consider painting the walls either a light salmon or light blue?

That fireplace and door arrangement is a booger for doing much in the way of seating that allows for enjoying the fire. I'd want to remove the door, but otherwise you probably need to consider the window view as your true focal point. Put a bench or pair of hassocks in front of the FP in winter when it is in use. Good place to sit and take off shoes/boots. Turn your rug 90 degrees so the same arrangement of chairs and sofa could face the window, chairs with their backs to it and a ceramic garden stool between them. This may be a case where the FP will mostly be ignored except when fired up.

Natural or faux greenery in several locations would add color, texture and warmth also.

Wow, what a place for a fireplace. And a door. Agree with deco, the view is your focal point, though I hate that the fireplace is ignored. Try her suggestion to rotate the seating so sofa faces window and chairs are in front of it. You might also try keeping your current arrangement, but moving the chair on the right to the other side of the fireplace so it faces the window.

Hannah, the pillows in my rendering were just google images, but the kilim I used is here along with a bunch of other cool ones: https://www.etsy.com/market/kilim_lumbar_set

The lamp is one of the Color + series from lampsplus.com.

Thanks for the extra views of the space. The rug is gorgeous now that I can really see it. And the case piece behind the sofa is beautiful, too. Lose the drapes, bring in some red and orange in the pillows, and the space will rock!

And please lower all your art a good 6". Eye level...when sitting down.

Raise the drapery rod and purchase longer drapes. Move in the chairs closer to the sofa to create a more intimate conversation area. Good luck!