I'm planning a last minute trip to the Istria area. We are driving from Kaiserslautern, Germany, will stop overnight in Berchtesgaden, then Lake Bled area for a day or two and down to Croatia for a few days before returning to Germany with an overnight in Hallstatt, Austria on our way home. On my must see in Istria list I have Opatija, Pula, Rovinj, Motovun and Grožnjan and then Piran, Predjama Castle and Skocjan Caves in Slovenia. What would you recommend being our base for these locations? Are there any you would consider must see over others if we run out of time? We are traveling with two year old twins and usually our vacations typically involve walking around and soaking up the scenery. Thanks!