This is one of the most beautiful (and expensive countries) I've ever visited. Things simply grow in Croatia.
Dubrovnik is the tourism capital of the country and worth every penny to visit. Sitting on the gorgeous Adriatic, Dubrovnik is a frequent tourist destination both for its historical beauty and being the recent setting of Game of Thrones (aka King's Landing). What many tourists miss is that Dubrovnik is also the jumping off point for Croatia's burgeoning wine industry. From here, the Pelješac peninsula and mainland Croatia provide some very interesting and growing wineries. Taking a tour into the Pelješac, Korčula or Istria is a must if you are nearby.
There are two ways to start in Croatia: via Zagreb or via Dubrovnik. The Istrian areas near Zagreb are accessible from nearby Slovenia and have varietals in common, namely Malvasia. From Zagreb, head south into Rijeka and west into Istria. Wineries are scattered around the small towns in this hilly peninsula. Or head inland for Riesling and Sauvignon Blanc.
From Dubrovnik, the options for winery visits are quite plentiful. Heading northeast, one can drive up the Dalmatian coast toward Ston. Tour buses and private tours are readily available and affordable, even though Dubrovnik is quite expensive. Visiting Dubrovnik is worth it. The seaside food is incredible and the atmosphere intoxicating and wine pairs with every meal perfectly. However, the true magic is Ston, Mali Ston, the Peljesač peninsula, Hvar and the many islands nearby. In Mali Ston, eat oysters on the seaside while drinking a great wine from the region. In Ston, tour one of the largest city walls in the world and stop for a great meal with a bottle of Dingač or Plavač Mali. From Ston, head west into the hills to meet the local winemakers. Quite often these are family affairs and you may meet the winemaker and his family!