I live in Antibes, 20 km from Nice.
The spots are pretty far from Nice :
You have Saint-Laurent du Var, close to the airport, but the spot is very small (probably not kiteable in Summer). There is rarely wind there
Then at Saint-Aygulf (70 km) you have a great sandy beach with reserved area for kite. Still you have to walk for 1 km to reach the spot.
And then at Hyere and l'Almanarre (140 km), you have some great spot which works for all wind direction. Here it's usually windy.
If you want to find some car to go kiting, you can use http://www.allosurf.net