We have a car and were planning to take a ferry to Venice for an overnight. They are expensive and the most regular ones leave from Croatia. We will be in SW Slovenia touring and wonder what everyone recommends-train from Trieste, drive in, or ferry. Time and money and ease are considerations.
I recommend spending a day/night in Rovinj and leave via ferry from here. Rovinj is super charming and a must see. We left our car in Rovinj while we were in Venice. The ferry leaves right from the old town and takes 3 hours. We used Venezia Lines.
For my trip in 2008, I was coming to Slovenia from Budapest. We flew from that city to Trieste, Italy (like $40), rented a car at the airport there and then drove around Slovenia. We then went to Venice, and dropped the car off there. Since we picked up and dropped off the car in one country (Italy), the cost
was pretty reasonable.