Bordeaux is a fine place to start. Here's a great itinerary I did a few years ago starting in Bordeaux:
Bordeaux->St. Emilion (pretty village surrounded by valuable vineyards; the grapes were being harvested when we were there)
St. Emilion->Bergerac (a visit to Monbazillac chateau/vineyard is worthwhile, just 7 km south of Bergerac, though a bit uphill)
Bergerac->Beynac (lots of places to visit, Josephine Baker's chateau "les Milandes", medieval fortress of Beynac, walled town of Domme, pretty village la Roque-Gageac)
A short detour north to the touristy but gorgeous Sarlat is worthwhile.
Beynac or Sarlat->Martel, a pretty medieval village not overrun with tourists
There are a number of superb sights a short distance south & east of Martel. The Gouffre de Padirac is a fantastic cave to visit. Rocomodour is very touristy but impressive. I found it more enjoyable to walk up & down the steps in the quiet evening after dark. Along this stretch of the Dordogne, there are a number of gorgeous villages, my favorite being Carennac. Other pretty places include Bretenoux, Beaulieu-sur-Dordogne, & St. Cere. You could easily spend several days visiting the diverse and outstanding sights here.
From Rocomodour or St. Cere, cross a few manageable hills SE to Figeac, a very pretty town.
Figeac->St.Cirq-lapopie, a stunning hillside village (going west down the Cele River until it meats the Lot, then a short distance up the lot to St. Cirq. En route, take a short detour from the Cele to the cave Pech-Merle).
St. Cirq up the Lot river (eastward), then south to Najac (via Villefranche), an isolated village in a buckle of the Aveyron river, high about the river. I happened to see an excellent documentary film about this village a few months ago. Alternatively, you could continue down the Lot river to Cahors, another pretty town.
Najac->Albi (via Cordes, another pretty medieval town). The landscape here looks very different from the Dordogne & Lot valleys.
Albi->Castres (or head to nearby Toulouse if you need to get home)
Castres->Carcassonne
With the exception of the immediate vicinity of Bordeaux and Toulouse, you should be able to select wonderful quiet roads with little traffic. Personally, I prefer to use the IGN 1:100,000 maps, but the Michelin 1:200,000 maps are sufficient.
I rode this with a friend about 8 years ago and we stayed in small, reasonably priced (2 star) hotels. We generally ate picnic lunches, but we ate superb dinners in restaurants each night. This region has some of the best cooking in France. PM me if you want names of specific hotels or restaurants. I have toured for years and years throughout the world, but this tour was as close to perfection as a tour can be. We began in mid-September and had perfect weather. I was back in the region last June and had pretty good weather then, too. If you are camping, there are loads of campgrounds.