If you looking for the quickest & easiest way to reach
Venice from
Rome, then Eurostar is the best option. Eurostar offers high-speed Italy trains service and you can reach with in 90mins hour from the Termini train station in Rome to the Santa Maria Novella train station in Florence, it's only a short trip. Eurostar
trains leave every 30 - 60 minutes, so according to your flight time, get an early morning train at Rome and make your trip comfortable. Italy train travel is reliable and inexpensive as well, so book your train ticket in advance to avoid disappointment. Hope this helps and have a good day!