Regensberg to Rome

What time of year? You have a lot of options.
The best scenic train ride would be the Bernina Express (or regular trains) from Chur, Switzerland to Tirano, Italy. You could stop in Pontresina for a few days on the way. Then connecting train to Varenna on Lake Como for a few days if you have not been there. Then it is a one hour train to Milan, where you can get a high speed train to Rome in a few hours.
There are lots of ways to connect the dots from Regensburg to Chur. Munich, Fuessen (for Neuschwanstein), Lindau on the Bodensee.

The train trip between Munich and Verona is very scenic. Highly recommend.

Many choices.

1) Munich, Berchtesgaden (Salzburg), Vienna, Innsbruck or into Slovenia, then Venice and train to Rome.

2) Munich, Augsburg, Oberammergau, Garmisch/Fussen, Innsbruck, Vaduz, Liechtenstein, Lucerne, Interlaken, Milan, train to Rome.

There is more if you want to deviate more geographically, like going to the Black Forest and Bodensee or the other direction to Prague and Budapest.

We will be traveling in August, I know, but that’s when the great fare for the river cruise was. We have been to Salzburg, Vienna, Prague, Chesky Crumlov, Milan and lake Como. We would like to spend our time in Barvaria, Switzerland or Austria. We will not have a car, but will be traveling by train. We are interested in staying for 2 or 3 days in a few really interesting small cities. Then do a scenic train ride through the alps ending somewhere in Italy. Then we can take a train back to Rome for our flight home. So some recommendations on interesting small cities and the most awesome train ride through the alps. Thanks