There are thousands of routes on the DLS as well as payware and freeware found elsewhere on the internet.
That said check out the various TANE routes by Phil Skene (Phil Skene). Among his routes are some narrow gauge logging style lines such as the Hoofarted and Smeltz. He creates the routes so that the content is easily found on the DLS and or built-in, which makes setting up the routes painless.
Clam1952 released some beautiful Welsh Narrow Gauge routes and there are many others of course such as the Legend of the BNSF which is found at
www.jointedrail.com You need to sign up, however, the access to the site is free. This route is a payware route with a recent upgrade due to be released really soon.
Then there are some new routes available on N3V's own store. A German designed route, a Russian commuter route, a recent Canadian freight operations routes, and many, many others to choose from.
In the end if you don't like what's offered you can always start the magical and addicting process of building your own route.
John