Readers should take note that fast Eurostar (ES) train service between Rome and Venice is now nearly hourly, and the trip now takes only 4.5 hours, although at a steep cost: about 65 Euros for a second class seat.
That fare looks even higher when expressed in U.S. dollars: about $95 at the current rate of exchange.
There are advance purchase discount fares for the ES trains, but they require a minimum of 7 days advance purchase.
Readers should also take note of a cost-savings alternative, which will save over 20 Euros ($30) per person: taking the mid-day Intercity (IC) train "Matilde Serao". The significant reduction in fare comes at the cost of greater travel time: six hours instead of 4.5 on the ES train.
(Also note that this IC train goes between Naples and Venice. The cost savings from Naples is even greater than from Rome)
IC trains are good trains, for the most part, even though they are not as fast as the ES trains, and make several additional stops en-route. There are eight second class and two first class railcars. And note that first class on the IC train is LESS EXPENSIVE than second class on the ES!!! There is no restaurant car, so travellers should remember to bring food and beverages with them. The IC trains are all non-smoking and air conditioned. All seats are automatically reserved upon ticket purchase. Reserve in advance and you may qualify for a 20% reduction with the "AMICA" fare (only on the IC).
Do your math and don't discard this IC train as a viable option between Rome and Venice. Ninety minutes more on the train will save you thirty U.S. dollars.