I've been there a couple of times. The Adriatic coast is gorgeous; coastal towns to see: Split, Rijeka, Senj, Dubrovnik (they've patched it up pretty well, I hear). There's an island off the coast called Korcula, where you can see Marco Polo's house. Montenegro is incredible! Plitvice Lakes (actually in Slovenia, I believe) are magical.

A lot of the hinterland is very beautiful and wild, and other parts are parched and drab. Have a great trip!

Cheers,
Michael