It really, really annoys me when sites assume they know which language you want to use from your IP address. And generally get it only partially correct. At the moment Blogger sometimes thinks I'm in England and sometimes in France, changing from English to French randomly and frequently.
Perhaps that is why I struggle with our shuttling back and forth between England and France - it happens too frequently, though not quite at random. Sometimes I wake up in the morning and have to think hard to work out where I am.