If you're coming from Madrid or Burgos, drive through the Picos de Europa to Santander. Pop over to Santillana del Mar to see the museum on the paintings in the nearby Altamira Caves. The next day, follow the Basque coast to Bilbao for a morning visit to the Guggenheim; move on to San Sebastián and lunch in the fishing port of Getaria. Drive through Pamplona and Navarra on your third day, approaching from the north if you're continuing across Spain, from the west (and then north) if you're France bound.
Coming from Madrid or Burgos, drive through the mountains on your way to the coast. Stop in Santillana del Mar and then detour west to Comillas and San Vicente de la Barquera. In Santander, check out the beach scene and wander around the Plaza Porticada. On Day 2, explore Laredo and Castro-Urdiales. Stop in Bilbao to see the Guggenheim Museum and other top sights. Devote your third day to the Basque coast from Bilbao to San Sebastián, picking and choosing among Bermeo, Elantxobe, Lekeitio, Ondárroa, and Getaria, each of which outdoes the other in activity, color, and cuisine. Spend Day 4 in sybaritic San Sebastián. Spend your fifth day in Pamplona and the province of Navarra, from which you can continue through southern Navarra to the Basque capital, Vitoria. Tour La Rioja on Day 6: drive through Laguardia and Haro to the provincial capital, Logroño.