I think that the SWML from with Waterloo/Woking to Weymouth would be a good idea as it could a follow up of the SWML: Southampton to Bournemouth Route for TS but for TSW instead. With this you could include the Lymington Branch, The West Coast way line from and the Alton Line. Of course you could make it a modern version and have the trains as 158, 159, 442, 444, 450, 458, 455, 456, 707 and the 701 Aventra, or you could make it more retro/old school with Class 421, 422, 423, 442, 455, 456, 170, 50.
A great route it would be, that's pretty long nearly 110 miles more than double the longest route in the game, your asking for a lot there.
