Don't use retractable cables. They are substandard and the mechanism is heavy (relatively speaking) and fragile and then you end with a mess when it breaks.

Edit: as for the flat cables, I have hesitated over several vendors and discovered MonoPrice has them just this week and I put in an order, once they arrive I will report back. MonoPrice has an excellent reputation and I trust their cables without a doubt. I have ordered a 0.5ft to connect the switch or the laptop to the router, a 5ft and a 7ft one -- I think it's a good balance of distance vs bulk.