Depends what you are interested in. just for riding I would take the coast road to boulogne, the the rn1 to abbeville, then the a28 to Rouen, follow the signs for rn138/le mans/bordeaux then switch to the A13 to louviers/Evreux. at louviers switch to the N154 towards evereux then Nonancourt, get on teh rn12 towards alencon but turn off south at Mortagne. You are now in biker heaven. Head south on teh D 938 towards Le mans via Belleme and Bonnetable. after Bonnetable switch to teh B B20 BIS which takes you on a country road to teh rn23, missingthe city of Le mans altogether. Here head towards La Fleche for about 3 miles turn off towards Arnage. drive through the village and follow the D 307 to Saumur.. really good riding. At saumur follow the signs for niort/poitiers.. preferably niort for more good riding.....but by then you will be looking for somewhere to stop for teh night ( plug) there is excellent riding then all teh way to the pyrenees, which make excellent although tiring riding.
an alternative is, at saumur follow the road up teh loire valley, and come down the old rn 20. The only bit of peage in this is teh 80 cents from Rouen to louviers on the A13 but from teh Niort road it is easy to get to Campo les bains (missing all teh peages) which is very close to an unmanned crossing into Spain.