Just booked 2 weeks in Cologne 13th to 27th (covering all of the group stages). Hotel is 15 min train ride outside the centre.
Flight prices have increased a fair bit since last week. I'm Glasgow to Cologne via Stansted (EasyJet then Ryanair).
I'm planning to travel to matchday locations for Scotland games unless they're evening games 4 hours away.
Cologne is hosting 2 party zones. One in the Old Town and one on the other side of the river .
Cologne is good striking distance for Gelsenkirchen, Dortmund, Dusseldof and Frankfurt. A bit of a PITA for Hamburg, Berlin, Leipzig and Munich right enough.