Train needs to use italo if you take coach car. Trenitalia you need to take first car to get some quietness.
F is not much more than Coach if you buy early, like 45 to 60 days before.
italo has a special 2 to 8 persons travel together, very favorable pricing. Of course it does not fit those who travel alone. But it is a steal for those travel as a couple or more persons together.
OP does not really know much about Italy and how many good things Italy offers. So be it. Those like you and many others who know, would actually prefer more and more people put Italy on No Go List - make Italy Less Crowded by uninitiated visitors. 
