High speed trains from Milan to Rome and Napoli to Florence

Na - personally I find most high speed trains boring. There is not a lot of scenery along those routes and often times, a train will be running through areas where there is a lot of tree, shrub growth along the tracks hindering the view.

If you happen to see something that you'd like to photograph or just watch for a while, you might have room to sit in an unoccupied seat on the other side of the train. But generally-speaking...no. And these aren't like nice, slow, scenic routes through scenic areas - these high-speed trains don't really allow you to enjoy much scenery...BUT I do like the Tuscany parts.

What you're supposed to enjoy on these high-speed trains is Napoli > Firenze within 3 hours ;-)

Enjoy your trip!

At 300 kph (186 mph) to 360 kph (224 mph) you don't see a lot in detail and it goes past fairly fast. The reward is the quick arrival.

These major transportation corridors were developed on the flattest land. You'll be backtracking through a portion of the same track on these two trips. You could choose a longer, coastal route from Milan to Rome, 7 hours via Genoa instead of Florence, but it's also not rated as scenic by railway critics, so I'm not recommending that.

The sequence of the cities, north to south, is:
MILAN - FLORENCE - ROME - NAPOLI.

You should visit them in that order to avoid any backtracking. At most you should back track from Napoli to Rome to catch a flight home, since Naples has fewer air options.