Help? Le Mans to Central Massif area and beyond

folks, i'm leading a group of cars on our annual 5 day tour in May. We always pre-plan to try and get the best roads, or those most suited to our cars ( caterham type ).

In reality Day 1 + day 5 are straightforward as we have little wriggle room apart from getting there and back as direct as poss with a few detours.

But days 2-3-4 will see us start near Clermont Ferrand, going down to Millau for the 2nd night, back to Vichy for night 3 and over to Le Mans for night 4. Although i 'think' i have plotted a decent route i'd really appreciate any local knowledge.
we're after back roads, twisties and want to sample the best the region has to offer ( within the parameters of those places where we're booked into Hotels).

if anyone can help please drop me a mail to info@southernkitcars.com
i have the routes flshed out using TYRE software and could easily share those for review.
cheers
Mark