As I suggested in a prior post, Ston and Mali-Ston are worthwhile and can be combined with a visit to the wine country in the Peljesac area. An easy day trip and best with a driver so you can enjoy the scenery and taste at the wineries!
We enjoyed our driver (a war veteran who had some interesting stories) - and he picked us up in a very clean, modern Mercedes, wore a shirt and tie, and was an excellent driver.

When the cruise ships descend and take over the old town, we went to the docks at the harbor and negotiated with a boat captain to take us out on the water along the coast to the other harbor and back (about two hours) - very worthwhile and affordable.

If you want to know a bit more about Croatian wines before you go, there is a wonderful wine bar in the old town of Dubrovnik that has excellent wine flights, knowledgeable people - and they also do wine country trips with groups. We found that doing some wine flights at the start of our trip really helped with choosing wines in restaurants and at the wineries.

http://www.tripadvisor.com/Attractio..._Dalmatia.html