Thanks for all the help so far. I've modified the route to try and reduce the number of places. Now it goes:
- Amsterdam
- Heidelburg (A friend lives here so I would prefer to include it)
- Colmar
- Lucerne
- Salzburg
- Munich or Vienna
I also have two uncertain places, Cologne and Zurich, which I can't seem to get around using this route, so I've included them as places either to skip or to get off for a few hours at. I've also got a (short) contingency list of places I could day trip to in case I don't take to the main stops.
As far as including smaller or more rural places goes, I'd love to but I don't know any so please recommend me some :)
I'm really not fussy in terms of what I'd like to see or do. I'm up for museums, galleries, hiking, castles, concerts, whatever is on offer. The only reservations I have are about food & drink, for allergy reasons (celiac). I should also mention that I live in Europe so I'm fine with not doing somewhere exhaustively since I could go back some other time.
New map (it's point to point by the way, no backtracking planned):
https://imgur.com/SiUw131
One last point: since I've cut down on the number of German locations should I migrate this to a more general part of the forum?