[Sylvanfan]

Depending on your budget, a few nicely planned night trips on the train can get you some extra money to use another day. As an example, a trip from Paris to Berlin is an overnighter. Same with Zurich to Budapest. Rather than spend awake time traveling, you can wake up repositioned to get going the next day, and often that's a good day to do your laundry as you wait to check into the hostel.

If you have enough in a group, occasionally a cheaper hotel type room isn't a bad option. Usually nicer than a hostel, and some privacy where you don't have to lock up all your stuff. But if you are going to be there late June to early September, reserve as many rooms as you can.