If you're looking to just bang out the travel and get there quick, fly. When I've flown from Italy to Paris, fares are cheap. I opted for Air France (didn't want to deal with RyanAir) and were still able to snag flights for under $40.
If you're looking for more of an experience, I would absolutely recommend an overnight train! Thello runs overnight trains between Venice and Paris. https://www.thello.com/?iLangID=3 It's an awesome way to travel in my opinion, plus it saves you having to get a hotel for the night.