I did this, but started in Chicago. Had to visit my son in Boston, so I went there on the Lake shore and came back on the Cardinal just for fun. As you may suspect, it was a lot of train therapy as you say.
Chicago to Nashville would be a huge thing. It would be bachelor and bachelorette party express for sure. But if they connect Chicago to Nashville, why not continue to Atlanta and have a new north south route from Chicago to Florida? Seems like an easy one?