1

I would recomment lac de Sainte-Croix in the Verdon and a boattrip from le Lavandou to île de Port-Cros.

2

Languedoc offers so much, what are your interests?
Lots of vineyards (and wine tasting), ruined (and a few rebuilt) Cathar castles;
wonderful farmers markets and flea markets (foire brocante, vide-grenier); caves with prehistoric art or caves with fantastic mineral formations; all sorts of fetes in large and small towns, train rides in the Pyrenees (La Petite Train Jaune) or through mountain gorges and farm land from inland to Rivesaltes near Perpignan (Train du Pays Cathare et des Fenouilledes); there's the dodgy Rennes-le-Chateau which figured in the Da Vinci code (and is still part of all sorts of conspiracy theories); below that is Rennes-les-Bains where you can have a spa day; there is the Aude river and Lac Montbel as well as other, smaller rivers; there are various beaches all along the Med--some great, some good, some...forget them.
Do you plan on renting a house and travelling to see other places or do you plan on staying in hotels/chambres d'hotes and move from place to place?
Tell me what you'd like to know more about and what doesn't interest you and I'll respond.I've spent a lot of time (vacations for 10 years) in the Aude and Ariege...my preferences are biased of course, but who really (who travels) doesn't have biases?
You also didn't say how much time, or what sort of budget...those sort of things are very helpful.

3

A lot depends on what you are particularly interested in doing. Marseille is a great place but it's a big city rather than being typical of Provence.I would suggest you go to Aix, Arles or Cassis, any of which you can get to easily by public transport from Marseille. Arles is full of Roman ruins and has a cathedral and gives you easy access to the Camargue, Aix has fountains, Cezanne's studio, wonderful cafe life and a cathedral, Cassis is a small town by the sea with beaches, walks and great fish restaurants.

4

You can get a bus from Marseille to Cassis, or a train from the station to Cassis train station then a bus or taxi to the town centre).

5

It doesn't necessairly have to be at the coast........so what do you mean when going with friends to the Côte d'Azur?

6

Me and my friends are very culture, nature and leisure-oriented, so everything historic, parcs ... That's all we need.
What I might have forgotten to mention is that I've already done most of the Cathar Castles in the Languedoc (what I might do again someday, but something new would be superb).

Some people didn't recommend Marseille, because there is a lot of crime (read: thefts) there. Is this actually true?
Nice would be pretty sweet, but I'm afraid it's really expensive.

7

It'd be a week or something and low-budget, considering I'm still studying and have to rely on the money I earn doing a job in vacation periods.