Thanks for all the suggestions. A friend who knows the island very well has strongly suggested we go to Strachan and the west coast but I think that our desire to not be too frenetic will win out. That will have to wait for another trip.
The current plan (and I know I'll need to do some bookings soon given the time of year) is: After a morning arrival into HBA drive to Port Arthur and spend the first night there. Then drive to Freycinet for two nights. Come back to Hobart for the final three nights in time to go to the markets, the next day to go to MONA and the final day to look around Hobart. Is this silly? Will the driving, such as it is, be reasonably scenic? Is there any variation I should do to this itinerary? Many thanks.