Joosten's route will be a cracker, he's only got 25 km to go I think.
I run the WM&B&O mega route a lot, end to end 300 miles so I lost track of what was going on. From portal 19+20+22-portal fairmont E+W 200 miles or portals 3E+W to portal clarksberg E+W 103 miles.
It's ok in 2010 native mode so will be fine in 2012, plenty of industries if you want to use them or just run end to end via the portals. Beware there are 2 hills you will need bankers, at rowlesberg for cranberry and keyser yard for 17 mile hill. It can take over an hour on 17 mile (I've altered/lowered the max accel on the locos) so you have to divert everyone else onto the other line and give them bankers so's not to hold the next train up.
Portals emit at 45 min intervals.