Itinerary advice please

Since you already have the flights there isn't a whole lot of room to change much. You only have one (probably jet lagged) partial day plus one full day in Dubrovnik. But that is actually probably enough, it doesn't leave time for any day trips but the city itself is small (and very crowded at that time of year). Make sure on your one full day you get up very early tot see the city before the cruise ships disgorge their masses. Also realize that a "1 hour flight" is going to eat up at least half a day once you include getting to/from airport, waiting, etc. So you will have two and a half days in Rovinj which should be enough for at least one day trip to some of the towns around there. I would actually change that to two nights in stead of three so you can spend the night at Plitvice. I have not been (am going in July) but everything I've read says it is horribly crowded mid day with day trippers so best to see the park after about 4 pm and before 10 am - which you can only do if you overnight. That is what we are planning on doing. Since you don't want to get there till after 4 you could spend the morning in Rovinj or visit more towns in the area before heading down to Plitvice. That would also mean you would get to Split earlier so you would have more like a day and a half there which is not much. We had three days there on our last trip and are going there again this coming trip - it's a very pleasant, interesting city. On our last trip we spent two days on Korcula and loved it.

This is a very rushed-feeling trip. Plitvice is magnificent. I hope you will take Isabel's advice so that the Plitvice stop, at least, lets you see it at its best. That means not treating it as a day-trip. I made that mistake in 2015, and it was not a good experience. I'm sure the park has only become more crowded since then. Aside from the thousands of people marching in lockstep along the walkways, I don't think you want to spend an hour in the ticket line (as I did).

This is a very fast paced trip, but you seemed to be locked in. Spend the night of day 6 near Plitvice, otherwise you'll arrive midday when it's the most crowded. Drop off your rental car upon arrival in Split as it's unlikely you'll need it while there. Timing of the catamarans is such that you'll probably want to spend the night in Korcula. Check schedules for both Krilo and Jadrolinija to determine the best sailing times for you, and buy both catamaran tickets (Split-Korcula and Korcula-Dubrovnik) upon arrival in Split. Both companies have ticket kiosks at the port end of the Riva, and the people working in the kiosks are very helpful.

Another vote for spending the night at Plitvice.

You could easily add another night or 2 to Rovinj to cover the hill towns.

The island element is rushed and with limited travel to and from the islands each day, I would spend an extra day in Split and visit Brac or Hvar as a day trip. Much of the accommodation on the islands have a 3 night minimum stay. Trogir is worth a half day trip from Split.

Thanks so much for the advice. I originally planned on an overnight in Plitvice, but then read in RS that you only need 3-4 hours. I planned on buying tickets online beforehand to avoid a line. We were planning on leaving extra early to get there around 10 AM. But I can see how being on a timetable to get to split could be stressful. As for the islands I’ll look into a day trip instead. I see mixed feelings on staying in Rovinj for 3 nights, but we are actually most excited about Istria, including driving around.

While 3-4 hours sounds like a lot of time, you'll be at Plitvice at a busy time of day at a busy time of year. When you factor in slowness on narrow walkways and waiting time for boats, you may find 3-4 hours rushed and be left wishing you had more time. One of the times I was there when it wasn't very busy, I spent more than 4 hours exploring the entire length of the park. If you drive to Plitvice in the evening, you don't loose that much time in Istria. You might use part of day 6 to explore towns on the eastern side of Istria and then head to Plitvice using the motorways. Plitvice is about an hour closer from Opatija.

Having done it (under less than pleasant conditions), I can say that you might be able to take the second-longest marked path through the park within 4 hours. However, 10 AM is not nearly early enough to make your visit to the park truly enjoyable. You need to be there when the park opens.

The last time I checked, I found no way to buy tickets online. That may have changed, but still I plead with you to spend the night there. Plitvice is a fabulous place. I saw it twice before it became so terribly crowded and again under miserable conditions in 2015. There is simply no comparison in the level of enjoyment.

Thanks again everyone. We have made adjustments and this is what it looks like
Day 1 Leave home (US)
Day 2 Arrive in Dubrovnik
Day 3 Dubrivnik
Day 4 Fly Dubrovnik to Pula. Get rental car and drive to Rovinj
Day 5 Rovinj
Day 6 Rovinj
Day 7 Rovinj to Plitvice via rental car
Day 8 Plitvice to Split, drop off rental car
Day 9 Split
Day 10 Split to Dubrovnik via boat
Day 11 Fly home (US)

BTW I found that you can buy tickets to get into Plitvice on TripAdvisor.

Oops...I just realized I am missing a day. Actually Day 11 is Dubrovnik and day 12 is fly home :)

Glad you added an overnight in Plitvice. We drove from Rovinj and stayed at Villa Lica, arriving in the early afternoon and spending the late afternoon hours in the park, mostly without crowds. People were walking out en masse as we arrived. The next morning we walked from Villa Lica into the park very, very early and enjoyed a few more uncrowded hours before the tour buses arrived. Villa Lica also had a very nice dinner and breakfast that we enjoyed. Once the park became unbearable - around 10am - and it was really awful by that time - as in, we could not even walk a normal pace on any path and had to wait our turn at any overlook area, we walked back through the woods, got the car and drove to Split. This was May 21-22.