My parents live in Avignon so I’ve been chipping down there with the road bike on the TGV a couple of times a year for a while now. The road riding really is fantastic if that’s your thing – quiet roads and great weather / scenery.
Get yourself a car. Public transport exists but the timetable is pretty sparse. The 20km in/out of town is a slog so I’ve been taking the new train service to Carpentras which is 10km from the base of Ventoux. Get up top, lunch at Renard and head down to Sault, then down Gorges de Nesque. Really great day.
Or head into the Luberon. There’s a fabulous closed road along the top from Robion to Bonnieux through the cedar forest.
Not done mtb but keep seeing chaps with full face helmets popping out of the woods on way up Ventoux.
Sites – Avignon can be done in a day. You can swim at the incredible Cascades du Sautadet – careful, serious accidents every year there or Pont du Garde. Villeneuve castle on other side is fun. Nimes – wonderful. Aix is cool. Marseille gritty of course. Bit further afield there’s the Ardeche – which becomes a car park in summer. It’s also roasting.