Best to fly into Zagreb.
– Plitvice national park: You can do a day trip from Zagreb with a rental car. It’s bout 150-200 km. from Zagreb and it is like a paradise; a creator lake with 7 levels. There’s nothing else to see in Plitvice town.
– It is common to rent a room at locals’ houses in Croatia.
– Stay one night in Plitvice, then head to Dalmatian coast, Trogir, Split.
– Stay in Split at least for a night. It is a city just like Rome but surprisingly not as famous. Good nightlife in Split.
– Take a ferry from Split to the islands: Pucisca, Makarska, Bol, Wild Bay, Hvar, Korcula, Dubrovnik. And do trip to the close by islands from Dubrovnik
– Croatia left to Bosnia only 20 km coastline. So when you drive in Croatia, you arrive in Bosnia for 20km and then go back into Croatia when this 20 km is over!