We (2 of us) want to go to Dubrovnik after spending sometime in Venice. As we do not want to fly, it appears that it is fairly expense, we like to drive and Croatian coast looking interesting, I have read that once in Croatia there are not any drop off fees from many of the rental agencies, but it looks like if we rent a car in Italy then drop off in Dubrovnik there are substantial fees. We would also like to drive into Montenegro once we settle in around Dubrovnik. So the big question is how do we get into Croatia to then rent a car? Would like to avoid going all the way to Zagreb if possible. I will also post on the "Boot" site. Thanks to all in advance.
What time of year are you going? Between about May and September, there are ferries from Venice to Rovinj and other ports in Istria. Check http://www.venezialines.com/ for schedules, which are not available yet for 2013. Or you can take a bus or train from Venice to Trieste, then a bus to Rijeka.
Charlene's question about season is valid, and will influence your options. My wife and I did some independent travel in that area after the ETBD Central Europe tour ended in Slovenia on Oct 1. We went by bus/train/air this time, but observed plenty of road miles while on the tour buses. The only high speed roads will charge a toll, which is worth it if you're just wanting to get somewhere. Expect speed limits to be 50 mph and lower in most other places, so you will get nowhere very fast. Great for seeing the scenery along the way. We took a bus day-trip to Kotor from Dubrovnik and enjoyed it. The road is good enough, but for a stretch under construction just north of the Montenegro border. Parking didn't look plentiful to me, but again, I wasn't really looking for that.
The general plan sounds great to me, just the details to work out. Enjoy!