Is there an acknowledged "best deal" for a mostly-German trip that may include day trips into France (Strasbourg) or Switzerland (Basel)? Something with reasonable costs back to the US or to the UK without absolutely GOUGING for a little bit of data? (We're going with our iPhone 4S handsets that will be unlocked).
If it matters, we're landing in Dusseldorf airport at the crack of dawn and will probably be taking a train to Berlin that day - in case there are convenient purchasing locations that might be more bsaed in reality pricing than an airport shop.