While it has been many yers, we did a 19 day tour of Italy that I put together. We trained from Salerno to Florence (took a non-stop) from Chiusi to Venice (also did not change trains) Venice to Novarra(no change) and then a 6 hour trip to Paris. All destinations were accomplished without changing trains (a blessing). Look for non-stops or no change required between destinations. We also took a day trip to Milano from Novarra. Only about 45 minutes. However, took another 45 to get out of the station! But it was fun. I always booked us in first class. Never give your luggage to an "attendant" Get it on and off yourself. One reason to pack light (smile) The Italian people are lovely. They are always willing to help. We took a bottle of wine and cheese, meat on our long trips. Wonderful way to experience train travel like a local.
We found that for an especially large train station it behooved us to check it out the day before we traveled. That way we could find our way MUCH easier!
Rail Europe is what I used the most. Hope this helps.
Barbara