If you get sick of the autoroute before you reach Grenoble, consider getting off it at Dijon( I always do as it gets you on the interesting stuff early!) and head to get on the N5 and head for Nyon in Switzerland. Over a small mountain range and as you head down to Nyon you see Lake Geneva ahead with the Swiss Alps in the background, stunning.Then head south to Annecy (gorgeous) Chambery,Grenoble.
Col du Galibier is a cracker. Had been beautifully resurfaced in 2004. We were there 3rd week in june and there was huge amounts of snow. The road had be cut out of the snow and but was not treacherous.
For Gorge Du Verdon, leave as early as you can in the morning to do the loop. Avoids a lot of the Dutch campeervans and tourist coaches. Take a spare set of footpegs as yours will be worn out!
It really is something special, road and views.
Last year we made the mistake of crossing the Millau bridge south to north. WRONG! Dilluted the experience somewhat as you basically come round a corner and ,bang, you are on it. N-South and you can see it approaching for miles.
Orange Michelin maps are best. Show you all the twisties/viewpoints.
Have a good 'un and mind and post some pics.