I've taken Amtrak long distance before (from DEN - IND)... It sucks. Big time. They have the lowest priority on the rails, so they are constantly pulling over to side tracks to allow the freight trains to pass. You also have to transfer trains, and it was in general a MAJOR pain in the ass. The reason I did it was to save money, since my brother was travelling with me too. Afterwards, I would have gladly paid double the air fare to not go through that again.