This year I am going to travel a bit south and get a few snaps of Mont Caragou near Prades.
I was down in this area a few years ago but unfortunately don't have my guide books or Froggie road atlas with me so these will be very general suggestions.
Do a few of the Cathar castles - the best are Montsegur, Peyrepertuse, Queribus and Puilaurens. Some of them can be a bit of a slog, especially Montsegur, as they're on high peaks but they're fantastic and the views, often across to another castle 10 or 20 miles, away are stunning. You can certainly see Peyrepertuse from Queribus and vice versa.
http://blog.m3.com/BackToTheStreet/files/montsegur.jpg.
Collioure and the other little fishing ports (eg Banyuls, Argeles) of the Cote Vermeille. The cote stretches for about 10 miles north and 5 miles south of the French/Spanish border. Very picturesque, but now rather touristy. This area is where Picasso and his contemporaries decamped to c1900 because of the stunning quality of the light.
Ceret in the Tech valley - nice provincial southern town with an important museum of modern art with Picassos and works by other artists who worked on the nearby coast.
The Gorges de la Fou - supposedly the narrowest driveable gorge in the world.
The cities of Perpignan, Narbonne, Montpellier and Beziers. Carcassone is very touristy but worth half a day, especially in the evening when the day trippers have gone.
The castle of Foix.
There are two small monasteries near Le Canigou - St Michel de Cuxa and St Martin du Canigou. Both very picturesque buildings in lovely settings and open to visitors, but no photography is allowed inside.
Andorra's a dump, but if you do go and buy stuff there make sure you return via the twisty Tet valley road towards Prades. If you leave Andorra heading north towards Ax les Therms, the police have places where they ambush non-French drivers and confiscate their purchases. And fine you.
There's also a mountain on which there are no fewer than 5 ruined castles from the middle ages - the Castles of Lastours in the Minervois. I believe they're floodlit at night and the best view (the only one I think of all 5 together) is from the terrace of a cafe which makes a charge for entry.
http://www.lespailhes.com/images/lastours3.gif
You might find some ideas here:
http://www.payscathare.org/
