You could take the train all the way. I did this (from Munich) many many years ago, and still have very fond memories of that trip. It's quite an adventure, and some of the scenery is quite stunning. The train line is now open again (having been severed in the 1990s as a result of the various wars in former Yugoslavia). Total journey time from Paris between 45 and 48 hours depending on your routeing.

The best place to look up international train connections in Europe is

http://reiseauskunft.bahn.de/bin/query.exe/en