While it has been a few years I stayed at and would recommend the Hotel Cezanne in Aix as it's a nice boutique hotel within walking distance of both the train station and Cours Mirabeau.

Each room seemed a different decor and mine while simple had a wonderful antique closet door that had so much character it was a focal point of the room and complimented the bed and desk. Windows looking out on to the street and shaded by trees really made for a nice room.

I went a little over my budget to stay here and was glad I did as it was a pleasant stay. I hope that helps and enjoy Aix.