rust orange.

First-- love that rug!

Second-- I'd go with a sapphire blue chair. Something like this, perhaps:

http://www.roomandboard.com/rnb/collection.do?method=get&id=4197457&cat=91552822

How about using the yellow color from your pillow there on the couch? I second the orange also.

A light orange shade would be great. We are redoing our bedroom in all brown, sky blue, white, and a pop of light orange. Make sure it's not too dark of an orange, I tried this at first with some pillows and it was not a good look.

Great room and a great start!
I would keep the cocktail table as-is, the wood top tones in beautifully with the wood floors and also picks up color in your throw pillows. Perhaps bring out the white in two side chairs (Louis-like or Heppelwhite sheild back)-paint the frame white and upholster in a more modern fabric. Then add a small, short table between and stack books on it. Maybe add a bench (Nelson-ish slat bench?) for additional seating...

If you leave the table as it, why not a white chair? Maybe a orange pillow or throw, which would be easier to change. Although brick red or tomato is my favorite color right now.

(sigh) I always go with neutrals for the major pieces. Sorry!

I would do a tan colored slipper chair with chocolate legs, and top it with a small rectangular lumbar pillow in a fabric similar to your curtains.

PS: I love your rug too!

I really like the rug. I have the same color combo in my living room and have been thinking of adding orange also.

A silver leather

My first thought was the same as the editors': Orange! A solid orange, or a ticking stripe or other pattern. That would be fabulous for a chair. With a nonmatchy blue pillow (like electric blue, or an intense aqua).

Option #1: Keep the table as is and get a white chair or something striped.

Option #2: Paint the table white and get a cafe au lait or pale tan chair

Use the orange for accents.

Maybe it's just me, but I think using orange to liven up a blue-brown combo is somewhat cliche. I personally would go for a gray... or white, or maybe an intense blue armchair, and then use bright pillows - yellow, maybe? - on both the couch and the armchair.

Though I like orange, I'm sick of its ubiquitousness these days. But if I wanted to go with orange, I would probably bring it in as pillows, rather than the color of the chair itself.

To me this room is screaming for red, not orange (I agree that orange is too trendy).

great start! my vote: Table as is, white chair w/light orange accent in pillow, artwork on the wall next to fireplace that picks up orange color, and lastly, 3 oranges in the bowl on the table :-)

p.s. try front legs of sofa on rug to avoid "floating couch syndrome"

Oh thanks everyone, for the suggestions!! I was so excited to see my living room up there!! Lots of fantastic ideas. Now I have to go in decision-making mode again... :-)

Based purely on color theory, orange would definitely liven up the blue, but IMO it would look very 70s when paired with the large, solid brown of the couch, and not in a good way - especially if you're planning on painting the tabletop white. I actually really like what the patterned throw pillow is doing with everything else in the room and could envision a chair in a fabric similar to that. The colors in the pillow are fairly muted but the pattern is what adds a little spice to the mix. Also, I think the yellow of the pillow would end up working better than an orange as an addition of a new color to the room. It doesn't look like your style is crazy wild, but you still want to keep things interesting. Some art and/or mirror on the walls will also help liven up the room too!

Maybe a pattern like this:

http://www.cb2.com/family.aspx?c=102&f=4320&q=briar loveseat&fromLocation=Search&DIMID=400001&SearchPage=1

yellow.

The table could stay as is--I'd find the chair and accessorize the walls before deciding.
A print could definitely work. My advice is to go to a fabric website (calico corners for example) and look at all of the blue fabrics--that's how you'll either find a print (with accent colors!) or decide you want a solid instead, but maybe get more pillow/accent color ideas.
If you go with a solid, have you considered green? I really like the green in that wavy patterned pillow.

Great call, PhillyLass. What a beautiful deep blue armchair.

Elvira, you have some lovely pieces. You could also inject an exciting punch of color by choosing a deep burgundy red for an armchair. (I did it in a similar hued room.)

pink!

- Instead of painting the table white, I think you might actually want to buy a new table. (a bigger one)

- But if not, I would keep the table as is, buy two room and board navy chairs that was suggested earlier.

- Another suggestion is about room layout. I think it would be cool to have the sofa/table face the fireplace, put two chairs on the opposite side with the fireplace in the middle. Two side tables and matching lamps around the sofa would be nice too. Just an idea :)

Yellow/gold

I echo phillylass' suggestion exactly. With the vibe I get from the room, your personality seems right for two of those sapphire blue chairs. I think it'll make you very happy.

I know everyone is all for orange, but blue-brown-and-orange just sounds heinous to me!

I must second Stephie_is_a_dork (so not!) - her suggestion stands out among others as the most elegant one (to me)!