We visited Pula in Isteria. We toured from Pula all the way north to the border by car. We stayed at the Hotel Histria in Pula. The town of Porec was also a very nice seaport town that offers beaches and many restaurants.
Isteria is also know for some nice wine, olive and truffles. You can tour many of the wine makers and olive makers as well. I would recommend that you visit Peter Poletti Wines near a town called Visnjon.
We stayed at the Hilton Imperial while in Dubrovnik. The best time to visit is during the days when the cruise ships are not in town. It makes for a crowded walk around the walled city. Overall, a must see visit.