There's a new webcam from Virtual Railfan which you can enjoy on YouTube from Tucson, Arizona. Here you will see Amtrak's Sunset Limited stop on there east-west runs. Here's an introduction [VIDEO]
This is a one-month demo so if nothing else if you go to Virtual Railfan's website you will be able to view the live action there. Though even if Tucson doesn't stay on YouTube on a permanent basis it might be up as cam of the week every now and then.
Here's the Amtrak Sunset Limited schedule and another interesting note that also attached to this train is a section of the Texas Eagle. Texas Eagle has a section that would continue from Chicago through San Antonio, Texas and west into Los Angeles, California. That section would be attached to the Sunset Limited in San Antonio and send those passengers on their way west.
I believe I shared that example on here once of such a trip.