This route has two possible start car-parks - or you could do it with 2 cars, as I did with a couple of friends from work. Using 2 cars saves the walk back along the roads to the car (around 5km of road walking). The full circuit is around 19km. The two parking options are at either 1100m or 1150m, and the summit is around 1910m; making this a climb of around 800m (although you have to drop down quite a lot from Col du Granier to get to the start point)
Given that the steepest walking section is on the north-east side of the mountain, parking at the Col de Granier, and working clockwise made the most sense to me, saving the more gentle incline for the descend. That said, we encountered a couple of locals who told us we were going the wrong way! We soon discovered why they said that - because on the way back down we discovered the path took a vertical descent, down several ladders. If you don’t like ladders - this isn’t the route for you.
The destination parking is at the south west corner of the route at La Plagne.
Grab the kmz for my planned route up Mont Granier from here, or take a look at the route plan and altitude profile below.