In my opinion, Brown is the ideal color for couches. This is because couches are suspect to stains and spills, So brown being a darker color makes these stains less visible and the life of the couch is extended.
There are a number of colors that go with Brown, if you are concerned about curtains. If you are into lighter shades, then beige or gold is your color. These colors will emphasize on the beauty of your couch and also make the room look wider and more sunny. You can also use a lighter shade of pistachio green to convey the same effect.
Apart from that if you want to give a bright look, use a mellow yellow or even rusty orange. It would make the room lively. And if you are a conservative, use shades of deep purple, green, gray or orange red.