We started from Vienna and after visiting our son elsewhere in Austria, we took a train to Ljubljana. We really loved Ljubljana - great hotel, great food, fun bike tour, cool castle to tour... From there, rented a car and drove to Lake Bled, over the Vrsic pass to the Soca river valley. After 2 days, we returned the car and took the train to Rijeka and rented a car to drive to Rovinj. We loved Rovinj and visited the basilica in Porec and two hill towns while we were there, but you would probably want a car to attempt this. I don't know if you plan to rent. Then we drove to Plitvice National park for one night, visiting the park in the late afternoon after everyone left, and the early morning before the crowds arrived. From Plitvice, we visited Split, Dubrovnik, Mostar and Kotor, driving from town to town. I think we have agreed that Kotor, in Montenegro, was our favorite - it was smaller and much less crowded than Split or Dubrovnik and we enjoyed climbing to the fort above town and take a boat trip up to Perast, but all of these towns are worth visiting. We also loved walking the walls in the late afternoon in Dubrovnik and a kayak trip we took there. We flew back to Vienna for a quick overnight before we headed home. Flights from Vienna to Dubrovnik are quick and easy.