Since I managed to lose my note to you, I'll just respond here in case there are others planning a similar tirp.

Toulouse to Carcassonne is an easy drive. Le Cite, the medieval castle,essentially the reason to visit Carcassonne is worth a stop. If you're going in summer, it's very touristy. The history is interesting and it's worthwhile to stroll around but two-three hours is probably enough.

From there, it's an easy drive to Narbonne--an interesting and beautiful city with one of the best covered markets in France. If you're a foodie, Les Halles definitely worth a stop, especially on a Sunday. Narbonne also has some interesting surrounding scenery--beaches, lagoons, but you might have to save that for another trip. If the timing is right, Narbonne might be a good place to spend the night.

I'm not sure what to tell you about Pezenas, it's beautiful, historic, also very touristy--and dead out of season. Lots of artist studios. I often go there for lunch. Maybe a quick stop then on to the Camargue--I've written about that here on Medium. Depending on how long you spend there, you could drive on to Arles and spend the night.

Arles & Nimes both have Roman arenas, artificers. Arles also has Van Gogh museum, history etc. So perhaps choose one or the other. My choice would be Arles.

From there you could drive on to Avignon--a walled city and definitely worth a visit.

Ooops, I just realised this schedule leaves out Montpellier. I'd definitely recommend spending time there, so one alternative to the schedule I've suggested is to go from Pezenas to Montpellier, spend the night there, then do the Camargue section the following day. If you decide to skip Pezenas, you could go to Montpellier after Narbonne.

I hope this helps, please feel free to ask any questions. One town you haven't mentioned is the fishing port of Sete--that would also be an interesting alternative to Pezenas. I've written about that too, I'll find both links and send them on a separate post.