As a left field suggestion, consider doing the Hurtigruten.

Otherwise consider a Eurail pass and just have the freedom to go from place to place.

Alternatively plant yourself somewhere nice and use it as a base for day trips.

Possiblilities would be:
Bruges (gorgeous old town, good food, good chocolate)
Innsbruck (good food, lovely old town, mountains, and don't miss the Alpine Zoo)
Lübeck (near Baltic, lovely old town, excellent marzipan, very important in Hanseatic League so lots of history)
Zürich (lovely old town, food, chocolate, history, mountains, lake)
Aachen (old, seat of Charlemagne, so lots of history, good food, and good chocolates. Sits at "corner" between Germany, Holland and Belgium)

Vienna is also possible, but I'd suggest you avoid the big cities, from what you've written.

I hope that that gives you some different ideas!

Audrey