I think something with some whites and oranges along with some blue would look really pretty and warm it up ... something like this ::

http://www.etsy.com/view_listing.php?listing_id=32122354

How about these Thomas Paul pillows...a bit of a splurge but would give the room some character:
http://pillowsandthrows.com/tpln0047aqu.html

http://www.cieladesign.com/

I agree with relish, and really like her/his suggestion. In fact, I used to have the same couch (but the sectional version) and also found it hard to get the cushions right because the blue is pretty bright. I think that curtains, and a rug under the coffee table would warm up the room too. In addition to those cushions relish mentioned, I think some dark chocolate brown either in the cusions, rug or curtains would cosy things up a little too. I also found that because of the fabric of the sofa, that velvety accents were too heavy. Good luck!

I have exactly the same sofa in the red. After much experimentation with various cushions I finally made four myself, each in a different blue-and-white fabric (one gingham, one striped, one large polka-dotted, one that fabric with the pictures of peasant scenes on it).

Because the colours in each cushion are each the same basic colour combination they really look well together without looking too matchy-matchy and are set off beautifully against the sofa. It also doesn't commit you to using the same accent colour elsewhere in the room (although of course you could). I keep two slightly overlapping in each corner of the sofa.

If you haven't guessed by now, my suggestion for you would be to do the same thing but with say red and white (I also really like the orange suggestion of somebody else, but it might be difficult to find enough fabrics in that colour).

I'd go with a burnt orange. It's the opposite of blue on the color wheel and would lend itself to the cozy look you're after. If, however, you plan to keep the walls white, you'd probably be better off with a chartreuse--work with the cool color scheme that's already there.

Christine
www.christineschwalmdesign.com

Orange or fucshia, or a brown print on a white background if you want to be more subtle.

I'd go with either an Orla Kiely style multi colored leaf print or maybe a pale green and white pattern - regardless I think a patterned pillow rather than a solid will break up the mass expanse of blue better.

yellow

moss green

Its a good idea to get FEATHERED filled pillows as they are soft and usually removable cover to be able to wash, instead of a firm polyester filled pillow.
A printed white pillow with colours suggested above ( such as orange, or even navy ) will complement the couch.
Or you could go with a "fluffy" ( looks like straight or curly fur ) textured pillow as well, those look great. ( either synthetic or real )

Also...

Use a large white/cream/or navy textured blanket either thrown in the corner of the couch; Or large enough to be a sort of "cover" for the couch ( where the arms are exposed )

this will also break up with couch and give it more interest.

Some other suggestions for your room:

-paint your wood table white and use it as a side table next to the couch instead of a coffee table ( its too small )

- add a beautiful glass / plexiglass table lamp on this small side table for light, and get rid of that old black deco floor lamp.

- remove the brass fireplace cover and find birch logs to place in the fireplace for decoration.

- clear off all the clutter on top of the fireplace mantle, as it looks junky and unorganized.
( add a mirror , or print, or some candles ) to keep it looking clean and modern.

Mod Diva's Etsy shop (http://www.etsy.com/shop.php?user_id=6698821&section_id=5870276) has a wide selection of modern pillows--many done in Marimekko fabrics--for under $20.

I've never actually ordered anything from her, so I can't attest to the quality, but I think the style of her pillows would pair nicely with the Karlstad. Try something in orange!

http://www.downtownshag.com/images/pillow-18x18.jpg

(Picture of fluffy pillow )

http://8rd.org/decoration/wp-content/uploads/2009/07/blue-sofa-and-doors.jpg

(example of what a white or cream large blanked covering your couch would look like )

gray and yellow!

Since your couch has streamlined armrests and softer edged cushions, avoid super slouchy pillows. Go for something that will showcase the armrests' simple clean lines. I would browse Etsy for a plethora of unique pillow options.

Pick something crisp and white or off-white.
Go for either texture details (like so):
http://www.etsy.com/view_listing.php?listing_id=32315960

or something graphic having a second highlight color (like this):
http://www.etsy.com/view_listing.php?listing_id=32584848

Four or five pillows on the couch will tone down the intensity of your blue couch, and little graphics or textures on the pillows will add interest instead of drawing attention to blocky or lumpy details. Don't forget to vary pillow sizes! The goal is to remain in the same style family without having quintuplets.

Keep adding colors and it's just going to be a mish-mash - Stick with a simple color pallet and you'll end up with a cohesive space.

I'd stick w/ Navy and White pillows - probably stripes - and replace the beige rug w/ one that's also Navy and white striped.

I'm thinking 1-2 linen pillows, maybe with subtle print designs - like those old french flour sacks. Here are some examples. Add interest through texture, not necessarily color.

Oh, and everything alicja25 said.

White and orange, like the first poster suggested, though these are my suggestions:

Coral and white

White, gray and orange

Orange and white in two patterns.

Sort of an Orla Kieley kind of thing, with more subtle colors.

Bright and striped.

Still sort of mod, but more neutral

Advanced: I think you need to swap your coffee table for something more rectangular (or get a new coffee table in a similar wood tone and use the existing one as a side table...then you could sell the torchiere lamp next to the couch and replace it with a basic IKEA number with an orange or white shade, or a thrifted lamp). A simple white rug under the couch and white curtains (over the blinds if you rent and can't remove them) would add some lightness. I'd also clear out some of the little things on the mantel and place a big mirror and white pillar candles, some art, a vase or two, or potted plants (in terracotta planters) there.

Just to clarify, not candles, a mirror, artwork, vases and plants. Pick a few things :)

thats what the OR was for :)

oops i thought you were referring to my post!
my bad

since the couch is heavy and square.
if its in the budget i recommend purchasing a rectangular coffee table with thin metal legs.
( chrome, bronze ) with a glass ( white glass, NOT green ) or stone top ( neutral colour... such as white or cream )

One of the newest posts on here shows a rectangular coffee table i described above :

http://www.apartmenttherapy.com/sf/room-for-color-2009/douglass-peaceful-peacock-living-room-room-for-color-west-22-098391

chocolate brown....

Try oranges like a rust or pumpkin orange with maybe a yellow or red accent pillow or throw blanket.

I think adding pillows with some brighter and contrasting colors plus white will lighten up the large bulk of the the blue sofa.
Something like this, perhaps a larger size to introduce ochre and white -
http://www.etsy.com/view_listing.php?ref=vl_other_2&listing_id=39019678