I agree with what a couple folks here have said: blue.  Go for a nice gray-blue, like a worn denim color.  It will go with the furniture you have now, plus it's an easy color to compliment with many different color accessories.

 I would pick a yellow . It's such a beautiful room. Have fun with it, and please post a picture when it's done?

like the blue also. Open up those windows while you're at it. That is a gorgeous room. I'm really digging the wood floors. As far as the fireplace area, you could paint that in a richer shade of blue than the rest of the walls to draw the eye to that focal point. Consider glass tiles in a rectangle over and around the fireplace area.You could paint and wipe away paint at parts of the fireplace in a similar shade of blue, but nothing major. We did that in shades of brown to a friends place. It turned out nicely.

I like that blue door in the background, I would go with a blue like that but a shade lighter. It's a lovely color.

check out www.benjaminmoore.com and click on color, then my personal color viewer. you can try out different colors there, like woodstock tan for the body color, navajo red for the accent walls, and ivory white for the trim.

Hi Cracker. I love your space! The eames chair and the Mies Van de Roh Lounge Chair are beautiful. I would love to own those in my home. Like I said you have a  nice space. I think Ask the decorator gave you some nice neutral color options. If you are looking to add some more POP and richness to your space, I would suggest using some darker shade or red.This would compliment the brown, gold and black in your room. I would also  change the color of the blue door and switch out the area rug for something more contemporary. Keep the white curtains and add some more black and white photographs/artwork (i see you have some already on your fireplace. Let me know what you decide to do, and make sure to post pictures. I would love to see how this room changes. Thanks! 

Check out what kiddy did with brown, black, blue & lime green. Could work...!

You have a great furniture selection started already, which will make choosing a paint color very easy. Right now you have a wonderful nuetral color scheme: browns, tans, black, silver and white. If you want a very sophisticated, trendy look, keep the neutral color scheme. Paint the walls a deep brown or a light mocha and keep the trim white. It will make your living room look warm and inviting. If you decide to stray from the nuetral color scheme, you could try a blue like the ones you find in patterns that are blue and brown. You could also try a sage or olive green which will give the room a very natural, earthy appeal. If you decide to go with a color outside of the neutral color scheme, try adding a few colorful accessories to the room which will really make your new paint color look like it belongs. Best of wishes and good luck! Your living room looks beautiful already, and I hope you like it even more when you're finished!