I've been only up the coast from Staribar in Montenegro to Dubrovnik but have been to the Balkans a couple of times now.
However, besides spending a few KR to walk on the perimeter wall in Dubrovnik, there's all sorts of nooks and crannies along the coast for your discovery. If you take some of the side roads and get away from the coast and tourist areas, you will definitely find the real Croatia. There's even great tavernas and rotisseries to eat great with the local people.
Learn a few essential words, please, thank you, may I take your photo?, etc. (There's an app for that--Slovoed) and if offered slivovitz, take a swig and you'll have instant friends and great folks to photograph! Enjoy the beer and if offered, you'll find more friends and great subjects!
One of my favorite places just a bit south of Dubrovnik was Kotorska. A drive along the perimeter of the bay could easily take a couple of days with all the little towns, especially the old walled town of Kotor, a former fortress left over from when Venice ruled the land.
Before you go, get into pretty good shape since along the coast, walking isn't on a beach, it's up and down the steep coastal mountains. Even a couple of weeks of walking before your trip will come in handy!
Have a great trip!