George Bernard Shaw called Dubrovnik The Pearl of the Adriatic and its true that this city on the Adriatic is possibly the best walled city in the world.
Croatia has more than a thousand islands. Many of them are connected to the mainland by ferries or you can even get an island cruise. We did this and although it was enjoyable next time I think I’d go for a little bit more luxury. Our cabin although clean was just a bit too minimal and pitch black because it was below decks. Also a week of meals on deck at set times stopped being so much fun half way through. I like to choose my meal and coffee times! Next time we will go for an upgrade!
Zadar, on the Adriatic coast, is a great mixture of ruins and innovation. There are Roman and Venetian ruins in the old town right next to a solar light show and a sea organ.
Zadar has a lovely atmosphere, much more relaxed and less of a tourist trap than Dubrovnik, but lots to see and plenty of coffee shops (priorities!).