Sorry, didn't see your post until now. Depends on what your looking for: For cities, Florence and Milan, and Rome are awesomely beautiful. As for landscape Alto Badia/Südtirol is mountainous and my favourite, although some people would prefer Sardegna for that. As for the trains it's no issue to use them between two major cities, can't speak for the countryside, though. Never been further south than Rome, can't speak of that region. Actually most parts of Italy have their beauty would avoid Venice, though, as it's overcrowded and doesn't deserve all the praise it gets, in my honest opinion.