This route idea sounds like fun.  I was wondering if you got more information about taking bikes on the two day trip railroads.  Do they allow it?

Some info about biking around Durango can be found here:
http://www.crazyguyonabike.com/doc/2011bletcher

I have also imagined a different ride employing two Amtrak rides for the start and finish. In that case, it would be going from Reno, NV to the central valley, probably Red Bluff, CA.
A trip report covering a lot of that possible route can be found here: http://www.crazyguyonabike.com/doc/9456