Well, if you have not booked your room yet I would suggest staying in a hostel dorm with the most people (ie 10 person mixed) that way you do not have to rely on a common room to meet friends (and abroad were all stranger so people are eager to meet). All the cities that you have listed for where you are going are very walkable and the public transportation will make up for any really long distances. But beyond person to person contact I would not really know how to find out who is going to be where and what they're going to be doing, Also if you don't really know the area or what to do usually when you get off the train find a tourist kiosk (pretty common in touristy cities) and they should have cheap maps for the local sites, and a events schedule of what is going on while your in town.
Hope I helped, for any other vague and incomplete answers that you want you know where to find me. :-)