People generally don't want to install cables or mess with configuring a roaming vs extended network and that is why the other solutions are successful. You could spend a very long time wondering about the best way, or you could just pop down to Dixons or wherever and buy a cheap solution and apply it quickly and intelligently.
Spot on.
Sometimes changing the wifi channel makes no difference - because it's not always a noise issue; the intervening walls can cause loss of coverage. That's the problem in this house.