I wouldn't avoid motorways on principle, many French motorways take you through stunning scenery, Clermont Ferrand to Beziers for example taking you over the gorge du Tarn at Millau. The main thing is to decide how many hours per day you want to spend behind the wheel then pick a route to fit your schedule, I found 4 hours a day actual driving time enough in a 4/4 Sport giving plenty of time for stops and detours (and getting lost). Being careful where you park overnight is more important than 'secure' parking, in many out of the way French towns on street parking might be quite acceptable
