We downloaded the Deutsche Bahn app and purchased tickets in advance for our longer trips. Out of an abundance of caution, I printed out our tickets, in case my phone lost a charge, was stolen, or we lost internet access.
We were able to purchase the Super Sparpreis tickets by purchasing ahead of time. We took the train from Frankfurt Airport to Wuerzburg. We bought the tickets when we arrived, since we weren't sure if the plane would be late or how long it would take to get through customs and baggage claim.
When we were in Bavaria we stayed in Wuerzburg as our base to visit Rothenburg and Bamberg. We had to check our bags at the Wuerzburg Train station, since our apartment rental was not available when we arrived. The baggage check machine allowed us to use our US debit card, since we were able to use a pin.
In Wuerzburg we bought tickets at the machine for the Kulturfestung Linie Bus 9. This bus goes from the Residenz to the Fortress. We were able to see both sites in one day and have time to get back to the train station to pick up our luggage.
We purchased Bayern Tickets to make day trips to Bamberg and Rothenburg. The regional ticket also allowed us to take the tram to and from the train station. Rothenburg was not that crowded on a Friday in September.
In Bamberg we tried the Rauch Bier. The line for the beer starts before noon.
In Cochem on the Mosel, we visited Burg Eltz and Trier. Unfortunately I was only able to book two nights in Cochem, so we did not have time to visit vineyards or the Rhine. In Cochem we purchased the Rheinland-Pfaltz ticket for Burg Eltz and Trier. We purchased the tickets on the DB app on the day that we used them. We purchased a ticket for 2 adults.
When we went to Burg Eltz we were the only ones who took the bus to the castle, everyone else drove.
Trier is about 1/2 an hour from Cochem and had great Roman ruins and medieval churches.
Many of the towns we visited had events with food stands or music. We wanted to drink wine on the old bridge in Wuerzburg, but it was crowded and we didn't want to drink when we were jet lagged.