At Parigi's suggestion we stayed in Sare. We loved it so much we did a repeat trip a couple years later. While I cannot chime in on Ainhoa, I can tell you why we loved Sare. I think that Parigi's suggestion of thinking of the region as "Basque Region" is wise, rather than "French Basque, Spanish Basque". Over time it's belonged to both countries, sometime the people of the area claimed it belonged to no one but them. Everyone seems to speak Euskara, French and Spanish and occasionally someone will shock you with English.
But first, did you call the restaurant, Olhabidea? Perhaps a phone call will bring better luck. They serve lunch Th-Sunday, perhaps that works in your schedule. Or, give yourself a "vacation from the vacation" and book a room for that night? Maybe that's an option? That way you wouldn't have to drive after dining... just thinking out loud.
Most of what I'm going to write is repetition of what Parigi said. She is THE one to listen to. So much rich living and traveling experiences in France, and she's a wonderful sharer. If Parigi suggests a restaurant or an area, we go! We've never been disappointed.
The gite we stayed in had a large patio and back garden, with a view of the hills and La Rhune mountain, the entire village of Sare and we were IN the village. It was bucolic paradise! Because we had a kitchen, we didn't dine out in Sare much. We tend to have a larger lunch (often out while day-tripping) and have more of a picnic/tapas style dinner while traveling. But the village has a couple restaurants, a grocery store, a couple of lovely shops, a salon, a beautiful Basque style church, access to walking routes and more. On a clear day, head to La Rhune on the
unique train.
Sare is so close to Saint Jean de Luz, a lovely fishing village (more like a tiny city) where you can swim, shop, dine, etc. We spent several hot evenings at the beach there cooling down.
It's very close to San Sebastián, and we went twice each time. It's a lovely town, again on the beach where you can swim, take a boat tour or just walk around. The old town has amazing architecture and twisty alleys. This is a great place to experience tapas!
We visited Hondarribia - just a quick peek to see what it was -, Biarritz (a little too "precious" for us), Bayonne, Saint Jean Pied du Porte, Capbreton, and a few other little villages nearby. It was the perfect location for us. None of the day trips were too far, or too taxing. The food in the region was delicious, a lot of fresh fish and Basque black pork, and piment d'Espelette (which you can also visit if you're inclined).
Let us know where you choose. I have a great restaurant recommendation for Saint Jean de Luz, if you end up near there. What a great trip you'll have!
Laura