Marco Polo has this nice book, "Unterwegs mit dem Deutschland Ticket" which is an excellent guide to the main "routes" it's possible to travel and the places along the line. Yes, it's in German, but if you really want to take advantage of the DT it's worth getting.
Posted by
Schwerin
4307 posts
Interested people can also find travel tips in Germany by regional branches of Deutsche Bahn on this page (in German language):
https://regional.bahn.de/magazin