Itinerary advice - September

For the portion down south without the car, just figure out your timing with ferries or buses. For us what looked like a good plan was difficult because of Ferry schedules (we included Korcula). Planning at least two nights in Hvar is good, you just might only have the one day between the two night to enjoy it though, same with Dubrovnik, you will likely be travelling all day to get there, then either an early or late ferry on departure, meaning Dubrovnik in a practical sense becomes two days of activity with a half to full day of that devoted to Kotor.

Not sure how you are planning to handle the Plitvice Lakes National Park visit. Because of very high levels of visitors, you should plan to stay at the park the night before your visit so you can get a very early start and beat the day-trippers. Otherwise, you will not have a great experience. If you happen to arrive by mid-afternoon, others have reported that the end of the day is also a good time to see the park.

Thank you both for your
Fab advice,. Will spend late Avo and morning to explore plitvice on the overnight.
Love this forum for pointing out things you didn't think of.
Have found the Krilo catamaran from split departs 7.40 so will be into Hvar 9am and use this same
Service to get to Dubrovnik depart 9am arrive 12.
Hopefully we Can pre book. What did you think of Korcula (had trouble deciding between the 2 would love to do both but maxed out with time already)

Korcula was great, but what we ran into is the ferry arrived late in the evening, and at the time the only options were early departures to Dubrovnik...so it turned into 2 nights there. As long as transport connections work out it is fine, but Croatia is like the Greek Islands, you just may not be able to move around like you think, forcing you to take a slower pace (which is not all bad)