If we spend the first day exploring San Sebastian (mostly on foot?) and the last day on the French side in St. Jean de Luz and Biarritz (returning through Hondarribia) we only have one full day in the car to see a few highlights in the Spanish Basque area. (We are not interested in wine or getting a tan on a beach)

Which direction should we drive to make a round trip loop from San Sebastian? Are there any special little "must see" villages we could include on this mini tour?

Bilbao, for sure. It is fairly close, and you will get to see the Guggenheim Museum - a must see place!

There are dozens of "must see" villages in the País Vasco, but one day is far too short to do more then just skim the surface of a few of them.

I suggest you take a look at Maribel’s Guides to the País Vasco and Pays Basque for a little more information. They will also allow you to do a little more planning on this adventure (http://maribelsguides.com).

Pamplona is about an hour away

And in France, Biarritz and St Jean de Luz - two venerable seaside towns and resorts. Take the TrenEskro (sp?) commuter train from the heart of Donostia to Hendaye, France, the end of the line, then at the same station hop trains the few miles to St Jean or Biarritz - in case you don't want to drive. But very close.