Here's my suggestion. Take a look at the West Moreton System, specifically the Eastern section from Rosewood to Toowoomba. This is a freight-heavy system, but it also has a passenger service running on it. The section is 105km long (~65 miles) and has a reasonably sized yard at the Toowoomba end. It includes a number of bridges and tunnels, as well as a sizeable 470m (~1540ft) climb between Helidon and Toowoomba. Currently, the system is used mainly for coal freight from inner Queensland to the Port of Brisbane. In Rosewood, the West Moreton System terminates and transitions into the Brisbane Metropolitan System. A long-distance passenger service from Brisbane to Charleville (the Westlander) runs twice a week. Historically, the system was used for a variety of freight services. The main freight workhorse on this system is the QR 2300 class diesel loco, usually there's two of them pulling a 40-car coal train. The passenger service is run by locos from the 2470 class. These are both six-axle diesels with EMD prime movers. Why do I think this route might be appealing? Unlike suggested elsewhere, this is not a typical flat Australian route. It runs through varied terrain and nice landscapes, with grades of up to 2%. It might be interesting for people to play with the Queensland locos and rolling stock, and learn about the signalling systems. I also have a personal stake in this suggestion. I live close to this system and regularly see the 2300s going past. I even have a model of a 2300 on my model train table. What are potential drawbacks of this route? For one, it might not be appealing to people who like dense service timetables. This route does not have them. If there's a dozen trains going through the system in any one day, it's a lot. It might be more appealing with the right scenarios. Also, the entire system is restricted to 80km/h speeds (~50mph). This will make end-to-end trips quite long. Options: Go back in time when more diverse services ran on this route - Grain, livestock and other freight. Here is an infosheet on the entire system. Here are a few Youtube clips taken of trains along this route (full disclosure, the first one was done by me): This is just a suggestion - please treat it as such. I understand that there may be a reticence on DTG's side to implement routes like this, lack of broad appeal may be one of the reasons.