San Sebastián or the Algarve?

My choice would definitely be the Basque Country. San Seb is a foodie’s heaven. Whether dining at one of the many Michelin starred restos or wolfing down pinchos with a few glasses of txacoli, dining flavors are bold and delicious. Sightseeing and relaxing in San Seb is wonderful though it will be too chill for their beautiful beach. Take a day trip to Bilbao to stroll along the river, visit the market and wander through the Guggenheim. I feel the area has much more to see and enjoy than the Algarve.

If you want beach time, the weather is likely to be much better in the Algarve, but there is less to see and do here if you want culture. It sounds like you just want to chill, so I would opt for the Algarve - Tavira or Lagos. The food is excellent and great value, as is the wine and the Portuguese eat meals at “normal” eating hours. The one thing I don’t like about Spain is eating lunch at 3-4 pm and dinner at 10pm or later.

If you want something more cultural, head for San Sebastián.

No comparison, Basque Spain would be my choice. The Algarve isn't even the best part of Portugal.

I liked San Sebastian. I was there in April, however, and the place was rainy and chilly. I learned it's a place to visit in the summer months. Unfortunately, that's true of the Algarve too. I went there in June. The weather was fine and I was two or three weeks before the massive European vacationer traffic.

I'd expect rain in either place in October. If you want to enjoy good weather in October you probably need to go off the Atlantic coast and further south.

Bilbao has a better flight schedule to Lisbon than does San Sebastian, so I'd stay in Bilbao at least one night. Trains and buses are not convenient on this international connection, unless you want to take the overnight train from San Sebastian to Lisbon.

I would add that I did 3 nights in San Sebastian in 2018 and 1 night in Bilbao and we definately gave Bilbao the short shrift. Both are wonderful cities, very different, but the old town of Bilbao was delightful and the Pinxos scene more affordable and less full of instragramming foodies than San Sebastian. I can't compare it to the Algarve but we LOVED Spanish Basque region and plan on returning.

hey hey april
My BFF is French basque and still has family there. It’s beautiful countryside, green pastures and farm are worth seeing. Check out maribelguides.com for information about about Spanish and French basque regions.
Les halles in Bayonne has local food and artisan crafts. A market place to wonder in. Small villages, saint-jean-pied-de-port along the canal, a small tour thru them. Enjoy and have fun.
Aloha
GO NINERS!!

Hi
If you just want to relax the Algarve is better, even better if you like beach areas.
The big draws for the Algarve are the beaches and the weather.
In October the summer tourist season is over and is calmer and less crowded.
Be aware that some waterfront towns don't have a beach as they have barrier islands that require boat access or are somewhat inland in a bay / river area.
The Algarve is great for seafood ( 'cataplana' is a regional seafood specialty), and for almond based sweets - it's the almond growing area of Portugal.
Faro is the largest city in the Algarve and it has an international airport, a bus terminal, and train terminal, with trains to Lisbon.
Faro has barrier islands.
Algarve also has better weather, it's very close to North Africa ( think Sahara desert) and the winds from North Africa heat the whole south of Europe.
For cultural sites the Algarve is not as rich as they are up north.
Since you're are going to do a tour that will be rich in cultural sites and experiences, a nice relaxed acclimatization to Portugal is a good choice.
Happy travels

Thank you everyone for the feedback. We have been watching YouTube videos and doing more and more research this week. We are leaning towards the Gros neighborhood of San Sebastián. I’m thinking it will be a little quieter than staying in the old town, yet still give plenty of options for sea views, walks and of course Pinxtos. I’m afraid if the weather has already turned to rain the Algarve will be very boring.

The overnight train from San Sebastián to Lisbon is quite the experience. Used it (in a first class 2-bed compartment) last summer and loved it. Dated train but good food, comfy beds. The train sways a lot on some poor sections of track, though, so you will be woken up every now and then. Still worth a shot in my opinion.