We did this self same trip two years ago - almost 3 weeks in total - fantastic fun, although we went from Santander to Bilbao (guggenheim museum etc) and then on to Biarritz for 3 days (saved spain completely for next time!)
Beziers - try staying at ‘Le Porte Ouverte’ at Leuriens (just outside Beziers - very good, abt 60E a night for twin. When you leave Beziers, head up over the Millau Bridge (Tarn Valley) - stunning (designed by our very own Sir Norman Foster)!
If you head west from there (towards Rodez) you will drive thru some amazing scenery- Rodez itself is worth a night - attractive cathedral and old quarter. North west from Rodez (check your map carefully to find this place) you can visit Belcastel (look it up online!) - an old renovated castle which houses original collections of art etc by Dr Seuss (The Cat in the Hat), Osamu Tesuka (Astro Boy) and other fantastic animation artists. The village and the chateau are unforgettable, and are high on the ‘most beautiful village in France’ lists.
We stayed overnight at Brive (convenient, not recommended otherwise) on the way thru to Angouleme (stay in the old town centre at the Mercure, it has secure underground parking and is a beautiful building in a great location).
On your way across to Angouleme from Limoges, take half a day out and visit Oradour-sur-Glane (this is the French village, preserved as a memorial, which was wiped out by the Nazis in June 1944 - over 600 people massacred and all the buildings torched - all women and children locked in the church and firebombed…). Its a sobering experience how humans can behave towards each other.
From Angouleme its a short run to Jarnac and Cognac (between them they house most of the main cognac and brandy producers - Hennessy, Hine, Courvoisier etc). The Courvoisier headquarters on the river Charente is an ‘interesting’ afternoons viewing (make sure you aren’t driving anywhere afterwards!!).
From there you can head up to the Loire (stay on the ‘island’ at Saumur- several lovely hotels there) OR (better still) head for La Rochelle on the Atlantic coast (the harbour area and the park all the way down the side of the city to the sea / beach are both excellent).
I know you will enjoy the trip - during the daytime whilst driving, in 3 weeks (Aug / Sept 2008) we had the top up for a total of 2 hours (on the way to Toulouse from Biarritz / Tarbes)! Totally totally brilliant.
Oh, and don’t bother with Lourdes - it is tacky beyond belief and is not what France is about.
Merlin The Hammer