After doing a little research, we are looking at doing the following itin, and I would love some advice and/or thoughts about this:
Starting from Dubrovnik (arriving afternoon by car):
3 nights Dubrovnik (gives us 2 full days)
Ferry from Orebic to Korcula
2 nighs on Korcula
Korcula (Vela Luka) to Split
Split 2 nights
Zadar one night
Istria 2 nights

We will be arriving June 2
Thanks for any help

Should be nice!

I trust you realize that you don't need a car for this trip, except perhaps for Istria? And that having a car could make your life more complicated than it would be if you relied on public transportation?

The final part of your trip sounds rather rushed -- Zadar for just one night doesn't give you much time there, although it could work if you arrive early enough (giving little time to Split) or leave late enough (giving Istria exceeding little time). Actually, I'd say that 2 nights in Istria is very little, even if you get there early on the day you get there.

And I'm a bit surprised that you've left out the Plitvice Lakes National Park, not to mention the Krka National Park (which is more or less on your way). But maybe they aren't of interest to you.

Hope that helps!

Be careful of cruise ship days in Dubrovnik. I know from personal experience that cruise ship days ruin the town .

I second Kja:
Up to Zadar your plan is fine (book the car at the Vela Luka - Split ferry ahead). You can easily include Sibenik and the Krka Falls Park on your way to Zadar.
A drive from Zadar to the Western Istrian coast takes at least 6 hr without any intermediate stop or at least a full day if you travel over the Islands (car ferries Jablanec - Rab, Rab - Krk, Krk - Cres, Cres - Istria).
So you will have only 1 day for the exploration of Istria. That's not enough.

I so appreciate the comments
We have already been to Plitvice Lakes National Park on a prior trip (awesome), and we already have a car starting at another point;
So do you think that we should just skip Istria and concentrate more on the coast around Zadar and the Krka park there? We are limited with our time and can't stretch our days as we have to be back in Austria by a certain date.
I saw the scheduling and that we could buy tickets on the ferry Vela Luka to Split, but it said we did not have a reserved spot until we show up. Is there a way to actually reserve the time? I did not see it.

We are checking the cruise schedule for Dubrovnik and hoping thee is one day with lesser number of ships. I've seen that comment alot and hope we get lucky.

Thanks!

Where do you depart from?
The last bit (Zadar and Rovinj) seems rushed.

It depends on what you want to see and experience, but I think you would be wise to trim something from your current plan. If you skip Istria, you could spend a bit more time in Zadar, maybe Sibenik, maybe the Krka National Park (closer, I believe, to Sibenik than Zadar); maybe add time to Split and/or Trogir....