^ Downtown Bordeaux's been undergoing some significant refurbishment for a decade or so. That's how a lot of it looks well-off today, but I heard hundreds of times it looked neglected before. I think Marseille is in that kind of trouble, some neglect due to a lack of will from local politicians. There's nonetheless some money out there. Overall, France's Mediterranean coast is everything but poor and I wouldn't worry about them.
In fact, most concerns go to the northern regions (especially Nord-Pas-de-Calais and Lorraine) that have lost their manufacturing jobs over the past decades. That being said, I recently read Lille was not doing so bad now. I don't like their mayor. She's a pain nationwide, but she's also often mentioned for having done a pretty good job for her city.
So, I guess I have to give her credit for that.