14 nights in Spain- flying in/out of Barcelona

I've been to all of these cities and think they are all great, but more information from you would be helpful. What kinds of things are you and your husband most interested in? History, art, food, music, architecture, sports? That'll help shape your itinerary.

Though Toledo is an easy day trip from Madrid, I'd suggest, and I think a lot of other posters on this board would agree, spending at least one night there. It'll be more relaxing and you'll have some time without the tourist crowds. Depending on your interests, you might also do a day trip to Segovia. It's famous for its aqueduct and roast suckling pig, and the Alcazar and cathedral were just amazing. I also found it to be a really pleasant and attractive small city to wander about in.

I only spent a day in Bilbao, but felt it was very underrated. I had heard it described as industrial and generally unattractive, but I thought that sold the city short. Also, the old town is lovely and has some wonderful restaurants. I'd split your time in the Basque country 50/50 between Bilbao and San Sebastian.

Train routes across northern Spain aren't as straightforward as one might expect. Getting from Barcelona to Madrid is super easy, but Madrid to the Basque country (and certainly getting from the Basque country back to Barcelona) is a little less so (though absolutely doable). It's about five-six hours from Madrid to Bilbao or San Sebastian, and some trains are direct, some not. There is no direct train from either Bilbao or San Sebastian to Barcelona, and changing trains in Madrid usually also involves changing train stations. Depending on your amount of luggage and train tolerance, you might fly from Barcelona to Bilbao, and then make your way back for your trip home via Madrid.

Caroline

We were just in Spain in May and wound up taking a flight on Iberia from Madrid (after arriving from the States) to San Sebastian, as I looked into the various ways to get there and that made the most sense in terms of cost and timing. The flight was an hour, we were already at the airport vs. a 5-6 hour train or a 4-5 hr drive. I would fly into Barcelona, then take a local flight to Bilbao/San Sebastian, local flight to Madrid -- or do it in reverse. As for Toledo, we visited it as a day trip and it was more than enough for us -- we didn't get it it, I guess, and I don't think it was just the number of day trippers, but it just comes down to what interests you the most and spend your time there (we also don't like one-night stops).

Contrary to a statement above, there are trains between Barcelona and San Sebastián (5.5 hrs) or Bilbao (6.5 hrs). In San Sebastián case, I'd recommend it over flying. Suggested night allocation:
Get from Barcelona to Madrid on day 1: can you book an open jaw ticket into Madrid and out of Barcelona? Else, you can book a separate flight or train ticket, leaving enough margin for the connection.
Madrid 3 + 1 overnight Toledo (or daytrip)
Bilbao 3 (go by train)
S Sebastián 2 (go by bus)
Barcelona 5 (go by train)

All of the trips are easy by train except Bilbao to S Sebastián which is significantly faster by bus.
Train passes are inconvenient in Spain due to the need for reservations, you're better off with poin to point tickets.

Thanks for the recommendations! We are flying in and out of Barcelona, so no open-jaw flight this time. Since we enjoy the trains, we will stick with that as much as possible and pay point to point. We like a minimum of three nights in each place for lodging, but may go down to two for Bilbao.
From Barcelona we plan on day trips to Monserrat Monastery, Sitges and maybe Girona (is it too far for a day trip and is it worth it?).
From Madrid we’re thinking of day trips to El Escorial, Valley of the Fallen, Segovia and Toledo. Is it realistic to do El Escorial and Valley of the Fallen in one day? Is that best by train or bus or private tour?
Between Bilbao and San Sebastián, we’re going to day trip to Guernica. Any other must see towns in the middle or nearby? We’re not big museum people (but we will be going to the Picasso and Prada museums). We really love to visit the quirky RS hidden treasures!

So based on all this, is it best to go Barcelona- San Sebastián - Bilbao - Madrid- Barcelona or in reverse?

Again, thanks for all suggestions!

I think you've got too many day-trips planned for the length of your trip. When are you going to see Barcelona and Madrid? I love Girona and liked Sitges (not remotely in Girona's class); I haven't been to Montserrat. That's three days right there. Barcelona itself needs a rock-bottom minimum of 3 days (4 nights), and you may struggle with your sightseeing schedule with that little time. Don't forget that your arrival day may be basically worthless for sightseeing due to sleep-deprivation and jetlag. I count 12 nights as 11 sightseeing days, minus over half a day every time I change hotels.

I'm a fan of mixing big cities with smaller places. You could have a really nice trip by sticking to the areas around Barcelona and Madrid. Throwing the Basque Country into the mix really stresses the itinerary because those are two long travel legs. If you want to do San Sebastian and Bilbao (which I much preferred) on this trip, you're going to need to limit your day-trips from Barcelona and Madrid or not really see those cities at all.

Edited to add: I should also have mentioned that the Basque Country can be distinctly cool and wet even in mid-summer. I'd suggest going to timeanddate.com and looking at the historical day-by-day weather conditions for early October 2018, 2017, 2016, etc.

Unfortunately, with S Sebastián and Bilbao thrown in, you only have time for one day trip out of Madrid and one out of Barcelona. From the latter, I have no opinion on what is best, from the former, Toledo and Segovia are more interesting than El Escorial for most people.