[crb07]

If there is any way you can do it by boat you should consider it. There are some crewed charter sail boats that might be reasonable if you get a group of people to go together. The coastline is amazing and very protected because of all the islands and light winds in the summer. Water is still a bit cold through June. Kornati Park is really nice by boat.
If by land look into some of the ferry service side trips. You can leave your car on the main land and get dropped of in town on some of the islands, very old and lots to see. A little crowded until end of August. Early September is nice.
Montenegro is worth seeing if you are that close. I have been many times but only by boat so not really sure about getting around on land but have been told mid summer can be a bit crowded.