I've just returned from 3 weeks driving around Greece. We started picking up a car at Athens airport and drove to Nafplio then on to Monemvasia, Mystras, Dimitsana, Kalavryta and over the Rio Antirro bridge up to Lefkada. From there we went to Monodendri in the Zagori region, Meteora, the Pelion and back to Athens.
I will just post a link to the blog I wrote as it was written on the go so has all the details I'll forget if I try to write now. I actually haven't quite finished it (have the last few days in Greece to finish up yet) but will hopefully get it done soon!!
Thanks to all the wonderful people that answered my questions, all your advice was much appreciated.