A coal route through the Appalachian mountains would be a welcomed addition to TSW. Such routes as the old C&O or Clinchfield that include enhanced grades and tunnels. The coolest route would be the old Clinchfield route through the Natural Tunnel in Virginia as well as over the Clinchfield Viaduct.
I would really like to see some older EMD (besides the SD40-2, GP40-2, and GP38-2), GE and maybe even Alco units in TSW
I'm a big fan of interesting diesel locos that were either unreliable or were rare for one reason or another, such as Fairbanks-Morse, Alco, and Baldwin. If we get a 1950s-60s route, we need UP Sherman Hill, SP, WP, GN, PRR, B&O, C&O, N&W, ATSF, Virginian, Milwaukee Road, Clinchfield, etc. I really would love to see FM Trainmasters hauling coal on the PRR, SP, Virginian, or N&W. A UP 1950s Sherman Hill route could include a Gas Turbine loco. The Trainmasters would also be great on an SP 1950s-70s era route (Peninsula Corridor or Tehachapi Pass for example).