Whole country? Then also visit Zadar (where I spent two of my early years), and on the way down to Dubrovnik, don't miss Slapovi Krke (Krka Falls), which comes close to the Plitvice Lakes!

_{*Lunatic*, n.
One whose delusions are out of fashion.}

The whole place, including Slavonia? :D If you time your trip right, you can catch a traditional dress festival in Đakovo ("Đakovački Vezovi"). I think they still hold it every summer.