We've just spent 2 nights in Carcassonne which gave us 2 days to explore - this is ample really.
There is a real sense of being in 'another world'.
Carcassonne has a lot of history to it and is a superb destination for a short break.
The mediaeval city is breathtaking - and there are lots of shops selling soaps and pottery and lavender. Some may find it crass but I enjoyed looking round them!
The Cathedral of St Nazaire is also worth a visit and a walk around the ramparts is a must.
The so-called 'new town' is worth a visit and there are boat trips along the Canal du Midi and lots of nice shops (shoes & handbags to die for!)
We ate in the mediaeval city outside (in late October!) and enjoyed the steaks, salmon etc that we had. They do seem to eat a lot of duck and pork there - not a massive choice for vegetarians.
Prices were pretty reasonable (various menus from 12 to 30 euros for tourists) The quality of the food was excellent (as one might expect in France!) and the local rose wine was lovely :-)
The whole place is a photographer's dream.
The citadel on the hill really does have the 'wow' factor.