We will probably stay a few nights in Nuremberg this September, and am planning some possible day trips. Bamberg is top on my list, but also thinking about Wurzburg, Bayreuth, Coburg. Am wondering if any particular rail journey stands out as extra scenic?
There is no "extra scenic" rail line out of Nuremberg, but certainly the line to Bayreuth (and further on to Hof or Kulmbach) is landscapewise far the best. After Hersbruck(approx. 20 km east of N.) it meanders along the Pegnitz river first and the through lovely rolling farmland.
https://www.vgn.de/en/getting-around/
https://www.vgn.de/en/maps-timetables/
Check out Grafenberg and other places in the Frankish Schweiz. Buses and local trains are much more scenic than the main lines. Bamberg is definitely a great place though.
The line to Gräfenberg an similar others are dead end, so you'd have to return to Nürnberg. If you are looking for a train ride like that I'd suggest either N. to Simmelsdorf-Hüttenbach, may be with an hike from Schnaittach up to the Rothenberg fortress (45min) or Forchheim - Ebermannstadt
through the lovely Wiesent valley (on Sundays and holidays you could proceed by steam train to Behrlingersmühle in the middle of "Franconian Switzerland").
I was going to say, the section of the rail line on the way to Bayreuth between Hersbruck and Pegnitz is through a limestone gorge that is quite scenic. sla019 beat me to it.