Best way to see Croatia

Steve, I'm also considering visiting that area next year. Using a rental car is one option, but I suspect the transportation in Croatia may not be as abundant as other places in Europe. I'll most likely sign-up for the RS "Adriatic" tour, as (for me) that's the most efficient way to cover the main sights in Croatia and to learn something about the people, the food and the culture. Cheers!

Steve, one option is to fly into Dubrovnik. Stay there a few days. You can easily use public transit (bus and ferry) if you want to visit one or more of the islands off shore. Then use a rental car to travel north. Rick Steves is a big fan of Split; my personal opinion is that Split is worth only a day visit to Diocletian's Palace.
Rick Steves overlooks Trogir; I enjoyed the architecture and general ambiance of that tiny island city that is accessible by bridge. From there you can take the slower, scenic coast road, or the rapid new highway, that will take you north. Tell us how many days you have available and when you plan to travel. I'm sure you'll get lots of suggestions on routes and attractions.

The best way is probably some combination of modes. Ferry and bus are the most common as trains are limited. A rental car can also be an option, but I would consider that for spot trips as opposed to having a rental for the entire trip. For instance, when in Dubrovnik, maybe rent a car for a day or two to explore Montenegro or the area North of Dubrovnik. The hop the ferry to the islands for a while (a car would only be an expensive option on that portion of the trip) then back to the mainland, maybe bus between several main cities, then maybe a car again to explore Northern Croatia. Basically, like anywhere, a car becomes a liability in large cities and islands, so limit it to areas where space allows you to explore.

We did a combination of travel modes while visiting Croatia and Slovenia bus, train, car AND boat! We took a one week cruise about the Dalmatian Islands on an oldtime motor cruise ship. This was our favourite way of arriving at the islands by water. Breakfast and lunch was provided as was a tiny room. We're not talking Mega Cruise ship here! Maximum number of passengers was 15. Simplified figuring out the ferry schedule and where to sleep, too. Dubrovnik was easy to do on own. Bussed to Split/Trogir, rented a car to do Plitvice. Trained from northern Croatia to Slovenia and rented a car for a couple of days in addition to taking the bus while there.