I've been to both Avignon and Marseille.
Avignon has a great skatepark worth checking out
http://www.constructo.fr/avignon-84/The locals were who hang out there were willing to show me the street spots on a map so don't be afraid to ask them.
Nice brick bank spot near the train station, couple of fun marble thing here and there. Check out Circle Skateshop on your way to the park and ask them about the spots in the area.
There's a lot of things to do in Marseille, La Major is a good spot but definitely not the only one. The first that comes to my mind is the downhill hôtel de ville plaza, right in front of the big fancy hotel.
The skatepark of La Friche is a lot of fun. Go to Bud Skateshop and ask your way around. Awesome miniramp inside.
The bowl du prado of course, it's hard to skate but they recently built a smaller part right next to it which is good when it isn't crowded.
For drinks go to le petit nice, very cheap and lots of young people to meet. Lots of good cheap kebabs almost anywhere you'll go.
Their's some gnarly hills to bomb to.
Have fun and explore !