Here, I'll describe my transport choices, as I travel in 8 phases throughout Austria and Germany this coming summer. I've already posted travel plans in the subforums for Austria and Germany, respectively.
Various maps from Deutsche Bahn showing long-distance IC/ICE routes as well as regional train routes within various states and interstate areas provide a useful picture and guide about how and where I can best use the DT, and for destinations with long-distance trains.
Phase 1: Frankfurt am Main 🇩🇪
I’ll get a new subscription to the 63€ per month Deutschland-Ticket (DT), well before the departure flight to Europe. On arrival, the DT includes my ride on an S-Bahn train (line S8 or S9) from Frankfurt Airport’s regional train station (Regionalbahnhof) to Frankfurt am Main’s central station (Hauptbahnhof). The DT also takes care of the city-region transport, including U-Bahn, S-Bahn, bus, and tram. As far as I'm aware, the special-tourist Ebbelwei Express is not included with the DT.
Phase 2: Weimar 🇩🇪
I booked a separate long-distance InterCity Express train from Frankfurt am Main to Erfurt with Deutsche Bahn. From Erfurt, the regional train to Weimar is included with the DT. All city-transport within Weimar, as well as regional trains to and from Naumburg and to and from Jena, are included with the DT.
For long-distance trains, I tend to work with the desktop version of the Deutsche Bahn (DB) website. With a registered account, their “DB Navigator” mobile app lists my purchases and provides proof-of-purchase.
Phase 3: Berlin 🇩🇪
With the DT, it’s a regional train back to Erfurt from Weimar. I’ve booked a separate long-distance InterCity Express train with Deutsche Bahn from Erfurt to Berlin. In Berlin, the U-Bahn, S-Bahn, bus, tram, and city-ferry services are included with the DT, as well as regional trains to locations in surrounding Brandenburg state.
For the time being, I plan to use regional trains between Berlin and Schwerin, although route frequency (every 2 hours) and duration (2.5 hours) are a bit tricky. City-transport within Schwerin is included with the DT.
Phase 4: Vienna 🇦🇹
There are trains between Berlin and Vienna (via Prague), but a one-way journey is over 8 hours. So, I’ve got a one-way flight instead, as I need some of that daylight in Vienna.
In Vienna, I’ll already have a separate Wiener Linien 31-day ticket purchased with a registered account on their “WienMobil” mobile app, where my ticket resides as proof-of-payment.
The simplest and cheapest transport mode from Vienna airport to the city is an S-Bahn S7 train to Wien Mitte-Landstrasse or a train with Austria national railway ÖBB (e.g., RJ or RJX service) to Wien Hauptbahnhof. It’s a regional trip, because Vienna airport lies outside the city of Vienna. But I only need a fare that goes from the airport to the city limits.
On their website and on their “VOR A nach B” mobile app, the VOR regional transport authority includes “Wien Kernzonengrenze” (Vienna core zone border) as a destination. This is important, because I already have a "city" ticket. The VOR one-way adult fare from “Flughafen Wien” to “Wien Kernzonengrenze” is 2,20€, which I can purchase in the VOR mobile app or at one of the ticket machines inside Vienna airport’s train station.
Between Vienna and Linz, I got Westbahn tickets for their early-bird one-way fares for as low as 5 to 9€.
Phases 5 to 8 in the FIRST COMMENT BELOW ...