Croatian culture is a exquisite mix of Italian laid-backness and German efficiency. The people are very friendly and service is pretty good.
If you are looking for a “must-see” places in Croatia – Dubrovnik is definitely on of them. Since you’re renting a car and have a few days, take a trip to the Mediterranean coast. There are a lot of gorgeous small towns on the coast which are worth the visit, especially towards the south, where you will not have problems finding a hotel.
Take your look at the islands, such as Hvar or Korcula, they have a lot of wonderful places to see.
Zadar is at the top of the coast where the islands start. Very laid-back & friendly – still more of a Croat vacation town than Italian or German. Consider a day trip to the island of Pag while there.
If you have enough time, visit Pula in Istria, with Roman ruins. The Croatians managed to build quite OK motorway connections, it should be a 5-6 hours drive from Split, on the way back to Zagreb. The isles on Zadar Archipelago are also worth visiting, you can get taxi boats to uninhabited small islands. The lakes at Plitvice should be also on the must-see list.
You have more chances to find real Italian gelato in Istria, especially in the western (Slovenian) part of Istria (Piran, Portorozs). If you had time, you could also visit Piran.
Trogir-near Split is a small town which center is completely as it is was on roman times.
In Plitvice lakes, Brioni islands, Paklenica are located a most beautiful national parks.
Istra (istria) peninsula – it’s on the west of the country with some gorgeous roman cities like Pula, Rovinj and in the inland medieval towns like Motovun.