hdvrod - we are planning to do that route in the middle of March so we would be grateful for a report back when you do it. Especially on any alternatives you took.
To any of you who have done this in March we are planning to stop for the night in an Aire around Nevers/Moulins way and then try to do the "mountain" bit in a day and stop somewhere around Millau (or a bit South) the following night. Is that feasible please? Will the Aires near that route be busy at that time of year?
Moulins has an Aire and a camp site right beside the river, opposite the bulk of the town (don't think the campsite opens in winter at all). If you are driving down the N7/A77 and turn off at the first exit for Moulins town you have to cross the Allier via the bridge in the town centre. Once over the bridge (direction Bourbon L'Archambault / Souvigny) you are at a roundabout and turn left, you can just see the Aire to your left as you cross the bridge. There are all facilities if you walk back across the bridge including the most fabulous Art Nouveau café 'Grand Cafe' on the right side of the 'High Street'.
Moulins has a small Medieval centre, but there are better in France.
Back at the end of bridge Aire roundabout there is a medium sized Intermarche supermarket if you were to turn right, you can walk it from the Aire in max 5 minutes.
If you continue down to Clermont Ferrand there is a motorway Aire just after Clermont, maybe 5km after the last of the suburbs. If you park facing south you will, weather allowing, have a lovely gentle view of the hills and extinct volcanoes. Have overnighted there many times without any cause for concern, it's a very quiet area.
Last, the A77 from the A6 south of Paris to the end near Nevers is a very quiet AutoRoute. For a Class 2 MH it's 4.35 euros for a pretty and well designed AutoRoute with a number of really good small and one large Aire.