What cities to add in either Italy, Slovenia, or Croatia?

I can't help with the car/parking issues since I've always used public transportation.

I'm a bit concerned about the weather you may encounter since it appears that the post-cruise part of your trip does not begin until at least the second week of October and you are proposing to spend a lot of time in small towns where there aren't that many indoor activities. Ljubljana does have some museums, and of course a lot of cafes and shops. In that regard Zagreb is even better, so it might be an option if things turn ugly.

I was in Montenegro and Zagreb for the first 12 days of October 2015, and fall had arrived. It wasn't cold, but the hot temps were gone and rain was becoming more frequent. I don't know whether Istria is more temperate than Zagreb at that time of year.

I adore Plitvice but wouldn't want to go on a really wet day, so I'd be reluctant to make a non-cancellable hotel reservation there before a reliable weather forecast was available. If the weather's good, definitely go. It is special. Even in October I do think it is best to spend the night before your visit in or near the park so you can beat the day-trippers into the park. Heading there on Mon-Thur rather than the weekend might also help.

I've never been to Trieste but liked Padua a lot. It has quite a number of sights to see, and the historic area is very walkable. Vicenza and Verona are easy day-trips by public transportation. (You could taxi from RR station to old town, if necessary.) Many people speak highly of Ferrara, which i think is also rather close to Padua.

Thank you for the warning about the weather. I wonder how difficult it would be at that time of year to not book a stay at Plitvice and try finding a booking at the last minute if it looks like weather would permit. But that also means we'd still have to find someplace to stay on perhaps in Ljubjana if the trip to Plitvice appears to be a bad weather experience. Can I assume that the tourist trade in both Slovenia and Croatia in late October would be light enough for us to find last minute accommodations? Maybe we shouldn't book anything, but have contacts in mind as we make decisions along the way.

I also appreciate your suggestion that we spend a night in Plitvice ahead of our visit to the Park so we are there before at least some of the other tourists. Perhaps the one night stay if we have to have one should be the Padua or Trieste stop and we should allow 2 nights in Plitvice if the weather allows. That would give us an evening's rest before we head off for Rovinj and the hauling of luggage through city streets on foot.

So to summarize ...how about 1 night Padua or Trieste, 3 nights in Ljubjana (so we can day trip to Bled), and 2 nights at Plitvice booked day before (while staying in Ljubjana.) really a last minute decision. This leaves 2 nights before Rovinj left for last minute booking.

Also thanks for the Zagreb suggestion but my husband said no to that location early in our discussions. I think he would approve staying on longer in Slovenia instead.

I am biased in favor of flexibility and don't book hotels before leaving home except for the first destination. That approach is not for everyone, however, and it is not risk-free. I have never spent the night at Plitvice, so I have no experience with trying to make a last-minute reservation there. It didn't used to be a problem to day-trip to the park, but 2015 was a totally different experience, which is why I now warn everyone that Plitvice can be unbelievably swamped to the extent that it seriously affects ones enjoyment.

You can take a look at booking.com and see how many lodgings are located very near Plitvice, and you can monitor availability as your trip approaches. One thing to check on is the holiday situation. There was a Tuesday or Thursday holiday in Croatia during my trip, in the first half of October. Many folks in Zagreb turned it into a 4-day weekend. I was shocked at how many shops and restaurants were closed. I wonder whether folks tend to take jaunts into the countryside over that holiday period. That could really ratchet up demsnd gor rooms nesr tge park.

The more I think about it, the better I like the idea of booking a cancellable reservation and making the go/no-go decision 2 or 3 days out when you should have a pretty reliable weather forecast. Be careful about the cancellation rules, though. Plenty of if hotels I've looked at on booking.com have 3-day or longer cancellation periods.

Aside from not wanting to rush to get to Rovinj before dark, I doubt that 2 nights will be required at Plitvice. I suspect that you could walk the longest of the 3 marked routes considerably faster than the estimate shown on the signs (which I think may have been 5-6 hours).

Sounds unnecessary, but check that your car rental allows travel to Slovenia and Croatia. Slovenia requires a road use sticker for the car which you should purchase at the border (doublecheck - I'm remembering from about 8 years ago). If you're not from the EU, you need an International Driver's Permit from your home country's auto association.

We visited Trieste, the Istrian peninsula back in 1990 when it was still in Yugoslavia. We stayed in Rijeka, now in Croatia.

Trieste was a disappointment, consider skipping it.

We drove through Ljubjana, not sure how much the city has changed, but the scenery was the most notable item.

The Dalmatian coast is beautiful with mountains coming down to the Adriatic.

Years later, we visited Split and Dubrovnik in Croatia that that was far more valuable than Istria.

The crowd situation in Dubrovnik has gotten much worse in recent years. Not that the coastal cities in Istria are non-touristy themselves.

I find Ljubljana charming and lively. The tourist infrastructure in Slovenia and Croatia has improved greatly since the split-up of Yugoslavia.

Between venice and slovenia on A4 is aquileia w amazing mosaics from the 4th century. Worth a lunch stop at least

We were in Slovenia and Croatia two years ago at about the same time of the year. It rained the entire trip, and, as the month goes on, accommodations for tourists closed down, particularly the ferries out to the islands off the Croatian coast. Even so, we had a fantastic time.

I second the idea of spending the night at Plitvice so you can get to the park early. We stayed in the park at a dull hotel with kind of lousy food, but the park is really spectacular. We entered the park when it opened and were literally the only people there for at least an hour. The drive in and out of that area is pretty interesting too.

We liked Rovinj but I actually preferred Pula which is more of a working town with a beautiful amphitheater and nice town square. My sister and her husband went to the artist town on Istria (I'm forgetting the name, but easily found in the guidebooks), and liked it very much. Unfortunately we had some trouble picking up our rental car, so we missed that part of our trip. Our hotel in Rovinj (a Rick Steves recommendation) provided parking for us.

I liked Ljubljana very much, Lake Bled and the Julian Alps. Gorgeous country. You might consider a stop at Kobarid, a town that was formerly part of Italy (known as Caporetto), a famous battle site of WWI. There is an excellent museum there which displays the horror that both sides, but mostly the Italians, suffered.

Have a great trip!

DD Traveler