Croatia Trip September

ILoveSwitzerland

My wife and I may head down to Croatia in September and wanted to know what are the must sees/do south of Rijeka.  Obviously we are aware of Trogir and Dubrovnik, but where else should we stop?  I would also like to visit Mostar and Sarejavo if the unrest has settled down.  Has anyone done this?  I am a train buff and wouldn't mind the trip from the coast to those places.  I would also like to do the trip from Bar up into the mountains (goes to Belgrade).  Has anyone done this?

We will probably use ACSI where possible.

Many thanks

Dixie