I concur w/ItalyBAGold, take the train. Driving can be far more challenging than in the states, and for your first trip, probably not worth the hassle. Do make advance reservations - if possible - for the train as summer can be very busy travel wise and you don't want to get stuck standing up during your journey. Also, the fare difference between 1st and 2nd class is not particularly great, so go ahead and get the 1st ticket for the added comfort and quiet.

Buon viaggio!