I've been to Split/Dubrovnik before and loved it but I don't know much about Istria. We were looking at Rovinj as a base.
Alternatively, I was also looking at the South of France. I was considering flying into Nimes or Marseille then going Aix-en-Provence followed by Antibes and flying home from Nice.
Has anyone been to both Istria and the South of France? Any advice as to which area is nicer?