Last month I drove down to near Grenoble, then on through the Alps in to Italy, Turin then down the Autostrada to Savona and the coast.
Fantastic time, the French Autoroutes are a little pricey, but well worth the money as they're clear, smooth and fairly fast moving. (only hold up was Lyon toll booth, 10 mins)
Plan your stops and be sensible about your distances you'll drive.
I hit Bourg D'oisans in one day from London and it left me a little fried.
Good place to stop over is Beaune near Dijon, proper little Burgundy wine town (Savigny les Beaune is surrounded with tiers of vines all it rows, very pretty)
A trip through the Alps is worth it, we took the back roads into Italy via Briancon, Guillestre, Vars over to Cuneo, all I can say is it's breath taking!
(was humming "on days like these" by Matt Monro all the way along)
The Autostarda, Turin to Savona is bonkers, probably the best motorway in Europe (not me but Clarkson)
Hairpin bends nailed 1000ft up the side of a mountain at 130kph with tin foil barriers, the hairpins are in and outside of tunnels!
Watch the locals use the hard shoulder and both lanes (and the central res) straight lining the corners!
Turin in a Panda? One of lifes dreams!!
If you're heading for Nice, skip the last part of the motorway and head from Grenoble through Gap and the mountains via Barcelonnette, give yourself plenty of time for it though, you'll not make good time, but the views are stunning.