One thing I would love to see in other route would be the Flying Scotsman. I hope the flying scotsman layers onto the GWE as well as Glossop, Birmingham cross city and Edingborough - Glasgow. As it is fairly realistic, it would add an extra special addition to the routes, in particular Birmingham cross city as it doesn't have a lot on the route in terms of layers,
Flying Scotsman has just recently been added to Midland Mainline and Fife Circle is having 6 Services added, for the other routes you could use the Free Roam options to put scotsman in those routes