We are in our last two days in Munich and would like to go to Berchtesgarden tomorrow using our three country Eurail pass. Germany, Italy and Switzerland. From the marienplatz or any barnhof in Munich. Can we do this in one day and do you have suggestions on the train and tour logistics?
The fastest way would be to go to the the Munich Hauptbahnhof and take a Railjet to Salzburg, but I don't think Salzburg is included in that pass, and then you would have to take a bus to Berchtesgaden and that also is not included in the pass.
If you go to Munich Ost Bahnhof (use any S-Bahn, which are included in your pass), then catch any train to Freilassing and take a train to Berchtesgaden. I think an RE from Ost Bahnhof to Freilassing actually has the fastest connection time with the train from Freilassing to Berchtesgaden.
Once in Berchtesgaden, purchase a RT bus ticket for RVO bus 838 to the Kehlstein (Eagles' Nest) Bus Abfahrt, either from the counter in front of the Bahnhof or from the driver. Get off the bus at the Dokumentation Center/Kehlstein BA stop. There you can purchase tickets for the special mountain buses that go up to the Eagles' Nest. After seeing the Eagles' Nest, be sure to visit the Dokumentation Center at the bottom of the mountain.