Madrid, Basque country itinerary help

Donostia/San Sebastián is definitely worth 3 nights with a daytrip to the castle-crowned town of Hondaribbia on the Spanish-French border.
Bilbao has a lot to see and dine on in its medieval city center near the Guggenheim. Two nights would be well spent in Bilbao. High-speed Renfe trains from Madrid reach Bilbao in 4:40.
You’ll definitely benefit from a car rental in Basque Country. You can then spontaneously stop off at interesting locations and towns you see en route to your next destination. You’ll also be able to get around more quickly as the train & bus service in Basque Country can be infrequent to many of the smaller towns. You’ll have the opportunity to visit the Rioja wine country outside of Bilbao and maybe the gigantic castle of Olite—about two hours from Bilbao and 90 minutes from San Sebastián.
For car rentals, check what is available at www.AutoEurope.com. They have cars available at Bilbao’s and Donostia/San Sebastián’s Airports.
Hertz does allow you to drive into France as long as you declare that is your plan before you pick up the keys. There may be a nominal surcharge. Donostia/San Sebastian’s airport is right by Hondaribbia on the border between Spain and France, so you can also pick up your car there.
The consensus seems to be that St. Jean de Luz and Bayonne have more of interest than Biarritz does.
You might find the small French Basque towns of Ainhoa and Espelette interesting to visit from St. Jean de Luz or Bayonne.
Remember to get an International Driver’s Permit ( IDP) from your nearby American Automobile Association office ahead of your trip. They now are legally required to drive in Spain and France as they translate your U.S. Driver’s license so it’s valid while you’re in Europe.
You can check airfares at www.Skyscanner.com. With a multi-city airline ticket, you could fly into Madrid and fly back from Bilbao or vice versa.
Have a great trip!

1. Yes, Bilbao is well worth a couple nights stay, for the Guggenheim, as well as the maritime museum, the city, and some good food.
2. Yes, San Sebastian is worth several nights, nice beach, a few sights, but the Pintxos bars are off the hook if you are a foodie.
3. Can't speak to the French side
4. To be honest, flying in and out of Madrid makes the most sense, direct flights, sure if cost makes sense, go with that. The only problem is that while fast trains in Spain make things efficient, the Basque region is not served well by train.
5. Crossing the border is not usually a problem, but let your rental company know, and do not rent in Spain expecting to drop off in France.

As a Bilbao local:

1. Is Bilbao worth to stay 1 night for Guggenheim museum or much more to do that better stay more than 1 night? Yes, it´s the biggest city in the Basque Country (350,000h, Donostia-San Sebastian 200,000h, Vitoria-Gasteiz (the capital) is 220,000h) and has many things to do and see. Food is very similar to that in D-SS, plenty of pintxos bars everywhere, and it´s not only the Guggenheim (great Fine Arts Museum, too).

2. Planning to spend 3 nights in San Sebastian, is it good or too long? It depends. This is a rainy area and beach weather is not always an option, so plan trips around the city (Getaria, Hondarribia...). Beautiful town, but you can see it in one day.

3. Then onto Saint Jean de luz and Biarritz, are those good to stay 2 nights or is it too long? I have heard Bayonne is better than Biarritz? Biarritz has a famous name, but nothing much there. Baiona-Bayonne is far more interesting.
   4.As far as I have researched, it seems like flying to Bilbao from Madrid seems best for us since we are thinking of getting flight back to states on same day of traveling back to Madrid from Bilbao. But any other suggestions would be appreciated too. We locals tend to use the bus over the train. Fast, cheap, modern, fully equipped, totally safe.

When you buy your tickets, if you do not plan to stay in Madrid, do not buy a ticket only to Madrid.
Buy tickets to Bilbao, which will have a connection in Madrid, but your bags will be checked through to Bilbao.
On the return, fly out of a different airport, maybe Santander or San Sebastián, or even Bayonne/Biarritz.
This will avoid backtracking and save you time.

Bayonne is beautiful, but for me, more interesting would be a drive inland to the smaller villages of the French Basque Country, including Sare and Espelette. You could do this in a day while stying in Bayonne, or you could even book a hotel in one of those villages. St Jean is pretty but will be mobbed with tourists at that time...but you could use it as a base for the inland villages.

Yes you can drive the car from Spain into France. Just let the agency know your plans.

You can never have too much time in San Sebastián, especially if you like food.

In my opinion, 1 night is too short for Bilbao and 3 nights in San Sebastian too long. Yes, the food is good, but there is great food all over the Basque country. San Sebastian is beautiful, but full of tourists. Bilbao, while there are certainly tourists, is less so, and I found it more interesting. We stayed in Hondarribia, and from there we took the bus to San Sebastian, and the car to explore the French Basque cities/towns. Hondarribia is a lovely town in its own right, easier with a car, great food and a convenient base from which to explore. Whatever you decide, it's a great area and you really can't go wrong.