In reply to Rog Wilko:
Cassis always seemed a pretty safe place to park to me, as a real tourist-town.
You can walk in to D'en Vau and a couple of others from Cassis, or there's a very handy boat option from there (to D'en Vau certainly, not sure about others) in peak season.
There's also an area (I forget the name) on the promontory due S of Marseille the we went to - seemed a pretty quiet little village to park in.
My impression is that the parking for the central calanques is the dodgiest. Of course i may have been kidding myself...