There seems to be a lot of questions about Kinect placement, so let me post this here:
Most suitable placement for Kinect:
• For a single player, ideally you want 6 feet (4ft works though)
• If you have two players, you want a bit more (8ft)
• If you want to control your Xbox from the couch while watching movies/tv, you don't want to be further than 11 ft
Vertically, you want to locate Kinect as low as you can (above a foot). 1 to 3 feet works best and you don't want to place it above 6 feet.
For those of you with sectionals, I would angle Kinect slightly so that it is facing towards the open side of your sectional. That is what I do and it works just fine. It is also okay to place it on the side of a TV, just remember to face Kinect as much as possible when you play.