Dalmatian coast

Budapest to the Dalmatian Coast to Ljubljana in 8 days is a lot. Fast and easy transit isn't a feature of this itinerary.

Split and Dubrovnik have airports; that's going to be the best bet from Budapest, although I don't know if there are any nonstops. If you aren't interested in non-coastal Croatia, you may want to fly from Split or Dubrovnik to Ljuljana. Check Skyscanner for flight options for your dates: https://www.skyscanner.com/

From Dubrovnik to Split, there's no train; you can take a bus, boat, or rental car.

From Split to Zabgreb to Ljubljana, there are trains; check the Bahn (German Rail) website http://reiseauskunft.bahn.de/bin/query.exe/en, following Rick's tutorial: http://www.ricksteves.com/travel-tips/transportation/trains/online-schedules.

Or you can drive the whole itinerary. For costs and estimated times, use the Via Michelin website: http://www.viamichelin.com/. Key word, of course, is "estimated"; also remember it doesn't take into account time you stop for refueling, bathroom breaks, meals, etc.

If you pick up a rental car in Croatia and drop it in Slovenia, you'll pay a drop charge; reports of these range from €50 to €600 (yes, six hundred euros). Even if you're driving the rest of the way, you may want to drop the car in Zagreb and take the train to Ljuljana; look at prices for both options before choosing.

Harold thanks so much for the quick and thorough reply. We would like to spend three nights on one of the dalmatian islands. Any favorites or suggestions for an island with great beach, good local vibe. We like to be active. From there we plan to drive to the istrian penisula and would like to stay in a town for 3 nights as a base for exploration.

Thanks Andee

You just need to do some legwork--what are your flight options, and what are your train options? Given that you want three days in Istria before heading to Slovenia, I would take a train to Zagreb and rent a car, and visit one of the islands in the north like Cres or Krk before heading up to Rovinj.