We will drive to Plitvice Lakes from Rovinj and have 2 nights lodging at the Lakes. Question is whether we should take our time to get there and plan to hike the next day and the following morning before we leave or should we plan to hurry to the lakes and hike that afternoon. I've read that the trails are really busy during the late morning and afternoon. We will drive from Plitvice to Split when we leave. Perhaps it would be better to not hike that morning and have lots of time for the drive to Split? I don't have a sense of whether it will be more interesting driving to Plitvice or to Split?
In Summer 2017 my wife and I drove the same route, but in reverse: Split to Plitvice Lakes (1 night) to Rovinj.
We arrived at Plitvice Parks at 2:30pm and were on the trails quickly. We then departed in the morning. That single afternoon was plenty sufficient for us to see the park, including a climb to a lookout. Two nights would have been too much.
The drive from Plitvice Park to Rovinj was nice. We stopped briefly in Otacac, then at a fantastic and unexpected viewpoint, and then had a wonderful seafood lunch along the waterfront inside the walls of Senj.
The drive from Split to Plitvice Park was shorter, and we only stopped at an ok viewpoint along the coast (to use the facilities) and then for an adequate lunch shortly before reaching Plitvice Park.
I posted a trip report on the forum; Parts 2 and 3 relate the drives. https://community.ricksteves.com/travel-forum/trip-reports/croatia-road-trip-aug-2017-dubrovnik-and-drive-to-split
We have also done the same drives. We left Rovinj in the morning and arrived at Plitvice in the early afternoon. I think we took some crazy route through the countryside there at the end because we were on some tiny roads that felt in the middle of nowhere. We were halfway lost, but we got there. The country side was striking for the shell-pocked abandoned homes and memorials on the road we were on. We went to the park for several hours that afternoon and it was wonderful. The next morning we got a very early start to see the rest of the park. By 10:30am it was unpleasantly crowded and we left for Split, but we didn't do any stops along the way. If I recall, we were in Split mid afternoon with plenty of time to walk around and enjoy it. I agree that if you can visit the park in the afternoon and early morning, one night at Plitvice is enough.