Hello wridenour, I can certainly recommend the layouts done by George Fisher and Dermmy for authentic American routes. There are also those by Phil Skene as his routes can be utilised for American Railroad operations and excellent fps running on your computer, and a number of other excellent creators such as Chris Racer, Doolinator, Leeferr and one by jrcrawford4 called Piedmont and Northern, which is well worth a download.
Edit: There is another good layout done by gandy-dancer - KUID 128675 - called Maine Central, he did several versions building the route up over a period of time, and certainly worth a look at.
Cheerz. ex-railwayman.