Hang a large painting or photograph on the wall opposite your couch. When you sit, you're in the perfect spot to sit and gaze at it, meditate on it or see new interpretations that you hadn't seen before. If your room dimensions allow, line up the art so that its center faces the exact center of your couch; symmetry is calming, whereas off-kilter perspectives might leave you feeling unsettled.
Emphasize and isolate your couch as a main focal point by placing a large rug underneath it. This is particularly effective if you have plain wooden floors or your carpet is one color, so experiment with a rug color that you can then bring out or enhance with one other small element, such as a vase or a lamp. Too many accents in the one color kills the effect, so be sparing with the accents, and let the color speak for itself.
Pull your drapes back when you're in, and keep your windows clear of distracting ornaments. Too much clutter around the windows and the sofa spoils the grand effect of a big area of glass, plus knickknacks collect dust from being by the window. Hang floor-length drapes for a dramatic look. Match size with size -- short drapes emphasize an imbalance between a large piece of furniture and small window coverings, and short drapes let in drafts in the winter as well.
Choose between soft, comfortable and inviting, or lean, elegant and chic. If you want comfort, pile your couch with pillows, textiles, soft rugs and cushions covered in sensuous fabrics, to make your window-gazing as inviting as possible. For elegance, think one or two neatly placed silk cushions, and keep the area as sparse as possible to accentuate the clean lines.
Follow feng shui principles, if your sofa faces the front door of your house or apartment, by putting a narrow table in front of the window and behind your sofa. Put plants on the table and an indoor tree at one or both ends to soften the effect of energy, or qi, leaving the room through the window and to dapple the light. This is also a good option if you have a dark sofa that might fade if it receives too much sun.