There are umpteen examples in Germany, a handful in Austria, and some interesting ones round Prague with historic locos and stock (also last summer in Slovakia).
This is a rather different category from the German equivalent of Dalesrail (where I posted my comment), although it is a one-off on a route that is otherwise all-ICE (as far as Munich). There are several daily IC trains to other holiday destinations, but they are all extensions of core IC routes (Oberstdorf, Lindau/Innsbruck, Westerland...).The daily Hamburg-Berchtesgaden IC would be the German example that springs to mind, but I half recall that hasn't run for a few years. I did it end to end once, it was a long but enjoyable trip in one of the beautiful 2+1-seated "half compartment" second class coaches - yes, second class - nicest thing in DB's fleet.
The Via Rail 'Canadian' is even more in that category...
Much of Amtrak outside "The Corridors" is just for the benefit of tourists. Services like Auto-Train almost wholly so.
... when I went it was worked by one of CP’s English Electric ‘Class 20’ locos.
OTOH the 2/day normal trains to Kanchanaburi (river Kwai) from the old west side of river station in BKK charge special higher farang=foreigner fares for the pleasure-most Thai using it travel for free anyway by some govmt. scheme. A farang single cost 100 THB=just over 2 GBP now.
Interesting question. Ilfeld-Nordhausen (largely operated by bimode trams) is definitely "proper," the Brocken definitely leisure, the rest of the network something inbetween, but pricey by German regional standards.Is the Harz Mountain railway a "proper" public railway or a heritage service?