Yes, it's another Croatia, BiH, Slovenia Itinerary Questions

calm down, please breathe.

First, Spilt is more than one day. we were just there and it was a terrific city. You can see Dubrovnik and surround in 2 nights. Mostar and surroundings. no more than 2 nights. Korcula 2 nights, Plivice 1 night.
Slovenia... you will wish you had more time.
Be ready for the greatest trip

Agree with pulling time from Mostar. That is one night in my opinion. Add more time to Slovenia. I also personally think 2 nights in Istria is enough.

We used GoOpti and they are reliable and very reasonable for your trek from Ljubljana to Venice.

A few thoughts:

• That's an awful lot of islands. It tends to take a while to get on and off islands because of ferry schedules. And there's a risk that you'll be jumping through hoops to see four islands that are not all distinctly different from each other. I can't help in that regard since I've never visited any of the islands on your list.

• With the many side trips you have planned, 4 days wouldn't seem to allow much time to Dubrovnik itself.

• I'm not familiar with Medjugorje, but it seems to be quite small. The population is under 2500, and typically only part of a town is of tourist interest. Are you sure there's enough there to keep you busy for two days?

• Your Plitvice night should be the one before you visit the park. After visiting the park, I'm not sure you can get to Istria by public transportation the same day. The best I can tell from the generally-useful BusCroatia website, you would need to go first to Karlovac (in the direction of Zagreb), then change buses there for Istria. You can play around with the schedule options offered on the BC website, but I don't know how predictive the early-October schedules are of what will be available next July.

• I'd hope to have at least 3 full days (probably better to have 4) in Istria so you could see Rovinj, Porec (different style of architecture), Pula (for the ruins), and the interior (Motovun and Groznjan are less touristy than the coast. Last year there was a once-a-week bus tour into the interior.) Vrsar is also nice for a quick stop between Rovinj and Porec. I haven't been to Pula so I have no opinion about its desirability as a base, but it is geographically isolated from the other spots I've suggested.

• There was bus service in 2015 between Ljubljana and Rovinj, but honestly, I think you'll find it difficult to squeeze in Slovenia. It's worth more than 2 or 3 days, and it fits well with a trip to Austria or Northern Italy. Maybe next time?

I have never driven in Europe; I used buses in Slovenia and Croatia on all of my visits. Pro's: A car would clearly be helpful to get from Plitvice to Istria and to see the Istrian interior. It would probably speed up your transportation to and from Mostar and Medjugorje, because international buses tend to run infrequently.

Con's: You wouldn't be able to drive into the historic areas of the cities you plan to visit, and parking could be a challenge in places, as well as costly. I don't know how it would work with your planned island visits. I assume it would cost substantially more to take a car on a ferry. If you decide to rent a car you'll probably need to drop it in Croatia to avoid high fees, and you must assure that you are permitted to take the car into Bosnia-Hercegovina.

No need to go to Split to get to Korcula, you can go after Mostar/Medjugorje (provided you rent a car, which I would with 4 people and this itinerary). I would stay at least three nights on the island.
I would look at the drive times on the viamichelin website.
Most people choose Rovinj for a base in Istria and just visit Pula to see the amphitheatre.
I wold skip Slovenia for this trip and add time to Croatia so you are not passing by so much without stopping.
You can drop the car in Rovinj and take a ferry to Venice.
If you are not interested in Split, you do not have to go there. If you are interested in three days in Mostar/Medjugorje, then do that--it's your trip! Definitely take the car though.

There were only two of us and we rented a car twice and were glad we did. With 4, it might also make financial sense. If you want to visit Istria and Plitvice and drive in the Julian Alps, you are likely going to want a car for at least part of the trip. I would arrive in Dubrovnik and see the town with no car and only rent when I was ready to head out of Dubrovnik - then you are not paying to park a car you don't need in town. We spent 2 nights in Kotor (one of our favorites), 1 night in Mostar (enough for us), 2 nights in Dubrovnik (arrived at noon, like you will, so had a good half day to start and did both a bike tour in some vineyards and a kayaking tour), 2 nights Split (agree that it would be easy to fill 2 full days - we did a bike tour that we loved and visited two museums), 1 night Plitvice, 2 nights Rovinj (stay there - it's lovely. We visited the basilica in Porec and 2 hill towns while we were there - would have like a 3rd night), 2 nights Kobarid (the WW1 museum is great and we kayaked on the soca and hiked to the waterfall), 2 nights Ljubljana (visited the castle and took a bike tour). We actually did this in reverse of what is listed, arriving by train in Ljubljana with no car to enjoy the town by foot and bicycle, then renting a car there for 2 nights to go to Kobarid, visiting Lake Bled, driving the Vrsic Pass, doing a kayaking trip on the Soca etc... It was a lot of driving, but lovely scenery with lots of stops. We returned that car to Ljubljana then took the train to Rijeka. Pleasant train ride and relatively easy walk to the Oryx Car rental office, then we had that car for 10 days, so we did, indeed, pay to park it and not use it in Split, Dubrovnik and Kotor, but it was great for getting from place to place and essential in Istria.

For Plitvice, leave wherever you are early and get there by 3 pm to spend the evening in the park - just spring for the 2 day pass - the evening is the best time to be there. Then go back first thing in the morning. Whatever you do, avoid 10am - 3pm. We stayed until noon the second day and could only shuffle along and could not see much over the mass of people.

We ultimately made the decision to skip the islands on this trip and come back to do that, perhaps by kayak or cruise, at some future date. For us it was May, and we thought the water would be chilly for our southern blood and we had so many places that we really wanted to see we just felt it was two trips.

As it is, the trip reads like it was crazy busy with no down time, but I spent all kinds of time sitting at cafes writing postcards, and we had wonderful, relaxing meals on most days, attended a concert in Dubrovnik, etc... The hardest days were driving to and from Plitvice and Mostar, and from Ljubljana through Bled and on to Kobarid - all long drives with significant stretches on narrow winding roads, but again, good scenery. We both agree that it was one of our best trips ever - Great towns, people, food etc...

We are planning a somewhat similar trip next summer, but we have a month to work with (and are trying to fit in Northern Italy also). Was also planning on (a) going south to north, and (b) having a car for most of the trip. My rough itinerary is as follows (so would appreciate the knowledgeable folks here giving thoughts, and any issues on the order of stops). Will have family of four on trip.

1 Dubrovnik
2 Dubrovnik
3 Dubrovnik (maybe hit kotor?)
4 korcula
5 korcula
6 Mostar
7 Mostar
8 split
9 hvar (or vis )
10 plitvice lakes (Zadar?)
11 istria and pula
12 rovinj and porec
13 istria generally
14 piran and Trieste
15 Ljubljana
16 lake bled and Julian alps
17 Venice
18 Venice
19 Venice
20 Venice
21 Padua
22 Verona
23 Dolomites (stay Bolzano or castelrotto or Val Gardena )
24 Dolomites
25 st moritz Switzerland
26 varenna on lake como
27 varenna on lake como
28 Milan
29 Milan
30 Milan (depart)

craig, since your trip is different from the OP's, you should start your own thread. Of course, continue to monitor this one for ideas.