Very briefly:
TOMAC, essential, as mentioned above. Continental Croatia’s best winery, hands down. They make a range of very impressive bubblies (by far Croatia’s best), as well as Croatia’s best, most elegant Riesling, Sauvignon Blanc and, often, Chardonnay (just tasted the 2015 white line-up some days ago, the Riesling and the SB are fantastic, the Chardonnay perhaps a touch weaker than it was in some previous years, I suppose the best fruit ended up in the bubblies). Also, far and away Croatia’s best and only truly successful Pinot Noir (personally, I find that Korak’s and Sember’s PNs, also from Plesivica, often lack balance, to cut a long story short… Tomac is a true virtuoso. His neighbours, some of them promising, still have some way to go, if you ask me).
ADZIC from Kutjevo in Slavonia also makes very beautiful Riesling and Pinot Gris.
Same general area, ENJINGI for highly personal, somewhat idiosyncratic, take-no-prisoners whites (profound, long and resonant at their best, but often heavy and, frankly, a little too extreme and ungainly for me…).
FRANO MILOS from Peljesac for Croatia’s best traditional reds (Plavac and Stagnum). The Rose’ is often quite exciting, too (2015 very, very good). Plus, the country’s best late-harvest Plavac Mali.
HRVOJ BAKOVIC from Brac Island for Murvica Plavac, a fabulous wine that regularly displays real ageing potential.
BURA’s best Dingac vintages are probably the most compelling modern-day case for this traditional terroir on Peljesac (Dingac is also made from Plavac Mali).
Try and find something from Vis Island. Paradox Bar in Split used to pour Neno ZOROTOVIC’s Zoborje, an occasionally incredible old-style white from very old Rukatac vines. ROKI’s for brilliant Bugava (IMO, coastal Croatia’s noblest and most interesting indigenous white variety) and Muskardin (a white blend). Toni BUNCIC has also been known to produce excellent whites when the vintage delivers, as well as a brilliant, Maury-style, sweet Plavac which he calls “Proshek”. Failing all of that, you can try and track down a bottle of LIPANOVIC’s Vugava, usually available in supermarkets - in a good vintage, this can be a very convincing wine. (If you drink Vugava, remember not to overchill it and drink from the biggest stems available).
Korcula Island’s most interesting grape varieties are Posip and Grk. I am not really a huge fan of anything that’s available on the market, but here are some of the better producers: KRAJANCIC, BIRE, SMOKVICA (a co-op). Avoid CARA (the biggest and most succesful co-op, completely soulless wines. (Posip is also made elsewhere, notably on Brac: STINA and, since very recently, BAKOVIC do a good job and their examples are probably more balanced and elegant than almost anything made on Korcula these days).
VUINA, from Kasteli near Split, makes excelent, authentic, gluggable entry-level wines: Babica and Plavac Mali. Worth tracking down, if you have a chance.
Then there is Istria, the northernmost section of the coast plus its hinterland. Being in a bit of a rush right now, I’ll just rattle off some names that I would be looking for if I were you: CORONICA, TRAPAN, DEGRASSI, PIQUENTUM, RITOSA…
Slightly disorganised, a bit of a bird’s eye view and, as I said, jotted down in a rush, but hopefully enough to keep you busy while there.
Many of these might be somewhat difficult to track down, but they really are worth the effort if compared to much more run-of-the-mill propositions you are likely to be faced with most places you go.
Safe travels and have fun!