I read on another post the Cinque Terre trains are packed in the summer. We'll be traveling from Genova south. Do the crowds on the trains subside by the third week of September?
Sure, somewhat. But not every train is completely packed and there are lots of trains. It all depends on where your are going and when. Don't worry about it.
Jon,
The crowds should be thinner in the third week of September, unless there are cruise ship groups in the area as they can pack a train to the rafters very quickly (I've experienced that and it's not pleasant, but thankfully the runs between towns are short).