I'm horrible at paint colors so I'll stay away from that one, but I found a couple options for your window seat cushions (but I'd buy swatches and double check the color first). Here's sort of a fun stripe: http://www.fabric.com/ProductDetail.aspx?ProductID=3d512c90-27e2-4729-b420-053984bb4015&CategoryID=4f25d96b-867a-46b7-929e-b51a0b46b550 A textured solid (although check the weight on it): http://www.fabric.com/ProductDetail.aspx?ProductID=a12595aa-809b-4a0c-b02f-6fdcf655cb4a&CategoryID=d9b6236e-3df0-49f9-97c1-4096858026f9 A great indoor/outdoor option (i.e. hard wearing): http://www.fabric.com/home-decor-fabric-outdoor-fabric-indoor-outdoor-texture-fabric-bryant-indoor-outdoor-marlin-linen-spa.aspx A more traditional print? http://www.fabric.com/home-decor-fabric-outdoor-fabric-indoor-outdoor-classic-traditional-fabric-bryant-indoor-outdoor-garrison-spa.aspx Another stripe: http://www.fabric.com/home-decor-fabric-outdoor-fabric-indoor-outdoor-striped-fabric-bryant-indoor-out-door-crestwood-stripe-spa.aspx http://www.fabric.com/home-decor-fabric-outdoor-fabric-indoor-outdoor-striped-fabric-waverly-sun-n-shade-brookline-mushroom.aspx I think it's the perfect place in the room to bring in a great pattern. Then you can bring in coordinating pillows that might be the same pillows you use on your couch that tie everything together. I really recommend something hard wearing because people often curl up on window seats and put their feet up there (and critters like them too). I've had great luck with microsuede and indoor/outdoor fabrics for the cushions and pillows on my kitchen banquette.

As apple pie said, your rug is the focal point, so for window treatments I would do a border drape…off white and preferably brown border if you can find the right tone. That will bring a darker color down to meet the rug…you find better than this…but it is the idea.. Maybe just two small lumbars on the sofa, but at the arms not the back were there is already lumbar support. Off white and brown chairs…from Anthropologie. Last a chunky fab throw for the sofa. ..

To clarify, you get 4 pillows with your purchase but only intend to used 2 at any given time, is that right? You want to use the 2nd set to swap out for seasonal decorating? I tend to want to have pillows make a statement rather than blend in, and I think the stripe and the two trellis patterns are too subtle. I like the one labeled Caviar, and the Hollyann Tangelo (though the tangelo doesn't say fall/winter to me, despite the color). What about a plain (or tone-on-tone) red?

It’s hard to comment when there is so little info. What does the rest of the room look like? If that’s the yellow for the bedding ( and your bedding?) which I’m sure you will be ironing I think you need to find a fabric you love to work from!