Yellow is a classic combo with cream and blue - French and most Sea - Ocean colour palettes use this combo. Yellow can be very difficult to live with when It's a painted room - I feel you need to keep it soft. Benjamin Moore has introduced a great new paint line Colour Stories. Keeping the paint finish as Matte ( which is not flat!) I would consider Shortbread. Or for a modern fresh twist consider Plaster of Paris.

Navy walls in a cobalt shade would be really stunning as the envelope does a cocoon type feel - here you will need to match the hue of your floor closely but not go quite as dark. Of course, gray would be very classic and work nicely - especially with a purple undertone like sw pussywillow. Yellows are warm and pretty - but only with white and ivory, they don't play well with beige at all. You also have to test them repeatedly in different lights to find the right one - they are the most susceptible to shifting for the light source and longitude, It would definitely work here with the sofa, but perhaps not with other elements you were considering. A warm, yellow based tan like camel is another classic option.

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How about interesting wall paper for the sofa wall?

"Sparrow" from Benjamin Moore. Looks great with blue (considering how the colour looks on my monitor) "sparrow" is a wonderful gray that looks great with burnt-red or orange accents

If you go with a yellow tone,may I suggest something more in the "mustard" realm? It's got some punch, looks great with navy and will work well with the existing wood trim. As you mentioned, a cream or beige would make the sofa look dingy. If you don't want the entire room done in mustard, how about an accent wall behind the sofa in mustard and a creamy white or pale blue for the rest of the room? Ask your paint supplier to help you pick tones and shades that work together. For an accent colour, you could use bright coral, orange, red or a fresh green!

Hi---I'm not sure if I'd add yellow. I think a large patterned wallpaper or a mural with soft hues would look nice. Pale wheat color for remaining walls---nice transition with the oak trim. Pic for inspiration. Good Luck!
http://www.muralsyourway.com/wheat-grasses-2-mural/

Hello again Karin. Because you mentioned that you would consider yellow for a wall colour, I couldn't resist collecting a few pics for you for inspiration. I have to say, that after searching for inspiration pics for you, NOW I want to do a navy and yellow room! If you use a yellow on the walls (whether paint or an accent wallpaper) it HAS to be the right yellow (otherwise it WILL look dingy) I have included these pics to demonstrate the numerous options that you have.

Just a couple more