We followed the route from Grenoble south to Cannes so that sounds perfectly do'able. Going down to Genoa and following the coast round to Cannes might be a nice way to start the trip. After Grenoble it looks like main road North East takes you straight to Annency - we came in from the West. Grenoble is lovely city to spend a couple of days - don't miss the Téléphérique up to the Bastille. Fabulous!