I agree with Deirdra, Aix en Provence is the place to go. It's a fabulous spot...bit like a mini Paris. Lots of life - loads of lovely narrow busy shopping streets, great fruit market place with lots of lovely cafes. Terrific spot. Been there a few times but never stay in Aix itself. Always a few miles outside. Base yourself in or near it and then do day trips to coastal areas such as Bandol - lovely seaside town. If you're into wine you could visit some of the wineries in this area. Not cheap but fantastic quality. The co-ops and supermarkets too have great value in wines and cheeses. Enjoy.
By the way, we visited Arles last year - spent two nights there and although it is a nice town I would advise just a one day visit. It is not nearly as nice as Aix and there is not really much to do. We also went to Avignon and again lovely for a day trip - nice walled old town worth a visit.