Need help with itinerary for Italy, Croatia and Slovenia

You may want a car to get you between the towns in your itinerary, however, once you arrive in pedestrianized cities where cars are unable to enter— cities such as Venice and Piran and Ljubljana— the question will be what do you do with a car that is of no use for a couple days and yet still must be parked at a pay parking lot somewhere outside of those cities’ centers. Not only will parking.become an expense, but auto rental agencies in Europe typically charge a hefty fee if you want to pick up a car in Italy and drop it off in any country other than Italy. Rental agencies also have surcharges to drive the car through a country other than the country you’re renting it in.
They sometimes charge for EVERY country you drive through. www.AutoEurope.com will show you exactly what you’re looking at in terms of the costs in renting a car.

My first thought is that you are going to spend far too much time, driving from place to place and changing hotels. It leaves you very little time to explore and enjoy the things/places you want to see. As mentioned previously, do your research on the drop off fee that will be charged by renting in Italy and dropping the car off in Slovenia. Those fees are normally very hefty. Driving through other countries often incurs another extra fee. We recently rented a car in Ljublijana and returned it there, the agency wanted to make sure we were not going to take the car out of Slovenia.

I wont comment on your number of nights and multiple stops.
You could rent the car near Venice mestre and return it there to avoid expensive charge for returning the car in Slovenia.
Also look if you can flyback home from Trieste or Venice. If Trieste is a possibility then return the car there.
From Rovinj, i would drive to Ljubjlana and spend the day there. Then drive to Bled. I would spent 3 nights in Bled, lots to see and do and less packing and unpacking.
Have a fun!

We rented a car from Venice airport to lake bled. Our "lunch" stop was at aquielia to see the mosaics at the 5th century basilica, absolutely worth a visit, it's a Unesco heritage site. at that time 2015? There was a little lunch kiosk there with pizza by the slice. Our mistake was spending too much time there, so that we were driving after dark to our destination and we found it incredibly difficult to interpret the minimal hwy markers. Full disclosure, one in our group lives part time in Slovenia, and one drives in the mountains of Oregon all of the time. And the remaining 2 of us are pretty astute..... but the hwy signage pretty much defeated the 4 of us.

Another thing to investigate is going by ferry, which might be beautiful. In full disclosure I haven't done this, but did plan it for a trip that had to be postponed. I also don't know how many "first timers" are involved, and that would impact the feasibility of what I'm about to say. You can and should train to Venice, and from there you can take a ferry to Piran easily enough, take the ferry to Rovinj, and then there is a ferry/bus combination that would get you to Ljubljana. All without any car rental. If you wanted a car to go to Bled, you could do that without incurring those big dropoff fees and complications of driving in different countries.

I suspect you may have limited options if you want to begin your trip back home from Ljubljana. There aren't a lot of flights out of that airport. Do a quick check on cost and travel time to be sure it looks as if it will be OK. If Ljubljana looks problematic, options include Zagreb (about 2-1/2 hours away by train or bus) or taking a GoOpti shuttle from Ljubljana to a useful airport to the west--probably Venice, if you can get a decent departure time out of that city.

It's easy to take the train from Ravenna to Venice. There will be a transfer in either Ferrara (smaller) or Bologna.

Ravenna has more than one full day's worth of sights in the form of magnificent Byzantine mosaics, a mosaic museum and an attractive historic center. Between the time before your cruise and the time after it, I hope you'll have time to take advantage of what there is to see in Ravenna. I liked Rovinj and have pleasant if vague memories of a brief visit to Piran in the 1990s, but to me Ravenna offers considerably more, and you'll be right there. I was thrilled the town still wasn't terribly full of tourists as of last September, but I wonder how much longer that will continue with all the cruise ships docking nearby.

Two nights is the minimum time I'd suggest in Venice, and if you weren't already in the area and no longer potentially dealing with jetlag, I'd urge you to stay a minimum of three nights. More time in Venice means more time to appreciate its charm away from the thronged areas around San Marco and the Rialto Bridge.

It seems you have 6 or 7 nights available after your cruise. I'd happily spend all that time in Ravenna, either Ferrara or Padua, and Venice. And that would be a squeeze. I loved Ljubljana, but it's a considerable push to get there from Ravenna by way of Istria, and it involves bypassing a lot of interesting places. Be sure Ljubljana's a viable departure airport for you, lest one of your precious days be required to reposition yourselves in another city.

So, you basically have 7 more nights to use? You could make a real case for staying in the Veneto. 3 nights in Venice, maybe a couple in Padua or Verona along with your stop in Ravenna will allow you to comfortably explore an under appreciated area.

If you’re dead set on Slovenia, which I’m not arguing against, I would probably forgo Rovinj and stay in Piran for those nights. Full disclosure, I have not visited either but my understanding is that they are similar (old Venetian empire port towns.) Trieste is also getting some love these days, so arranging travel via public transport with a night in Trieste to make it less hectic might be nice. I thought Bled was fine as a day trip and would stay all three nights in Ljubljana without hesitation.

I would be trying hard to avoid renting a car. It’s probably going to be expensive, with cross border drop offs and such. But mainly you’re not covering all that much area, or different sights. Definitely don’t bother until you’re on your way out of Italy. There’s bus connections between everything here (though sparse perhaps.) Ljubljana airport can be an expensive one to fly out of, and many people use nearby alternatives like Zagreb, Venice or in Austria. Still, if you book far enough ahead you might get a fair enough deal. I had looked at fares last year prior to Thanksgiving, thought they were high, and just a couple weeks later was paying the same amount to fly out of Zagreb. It might be something you have to make peace with.

Thanks for all of your suggestions and ideas. I have been to Venice and Verona area before so I really want to explore new places. I am definitely rethinking the rental car idea- just public transportation makes me nervous since it’s so foreign to me….but I know Europe does it much better than the US. Thank you everyone!!