Serbia has nice things to see (Tara mountain, Belgrade, etc.), but if you make a Balkan tour you should not skip Montenegro. They have everything - nice seacoas

Serbia has nice things to see (Tara mountain, Belgrade, etc.), but if you make a Balkan tour you should not skip Montenegro. They have everything - nice seacoast with a number of old cities, mountains, lakes... And it's all condensed in small country, meaning daily trips will give you a lot of variety. Just don't go there July-August since it's packed full of tourists and traffic jams are everywhere. May, June or September are the best.