Zaragoza

I’m sure Carlos will chime in, but yes Zaragoza is worth a full day or two. We thoroughly enjoyed our stay there last year.

if we only have several hours on our way to Madrid, is it worth stopping?

A few hours would be enough time to visit Basílica de Nuestra Señora del Pilar and the old town or the Aljafería Palace. I personally wasn’t impressed by most of the palace, but it is closer to the train station. I enjoyed the Basilica and old town. To me, to make the visit worth stopping for, at least four hours would be needed, not counting the time getting to/from the train station. Others will have differing opinions.

we'll be stopping in next week - any favorite restaurants in zaragoza that people would recommend?

We spent 3 days there in 2018. Really enjoyed it.
Firefighter Museum is excellent.
Origami Museum is great.
old Roman forum, the Teatro Romano and the ancient city walls.
Aljafería Palace is rich in history.

El Tubo district for food.
This egg dish is amazing https://www.tripadvisor.com/LocationPhotoDirectLink-g187448-d1319299-i251981707-Meli_Melo-Zaragoza_Province_of_Zaragoza_Aragon.html

While Zaragoza is an underrated gem, frankly I don't think you have enough time, if you have to travel from Barcelona to Madrid to fly out on the same day.

i was in zaragoza just a few days ago. i stayed for 2 full days. while the center is beautiful, it is some distance from the station if you only have a few hours. may not prove to be as memorable and worth the hassle in my opinion.

thanks everyone! Since we only have a few hours it looks like we should skip it! Appreciate eveyone's input.

I know you've made your decision not to stop, and this is for anyone else doing research. Zaragoza is wonderful! We spent two days there and loved the "realness" of a lovely Spanish town. Well, we were in the old town near El Tubo and The Basilica. The Basilica is spectacular and well worth time if you enjoy beautiful Catholic churches. Same for La SEO (Cathedral of the Savior of Zaragoza). The pedestrian-only shopping streets were such a joy and the Cristal Museum was beautiful. Tony Galvez has a YouTube Channel called Road Trip Spain and Portugal. There are at least a couple videos of Zaragoza and some on Madrid and Barcelona. They really helped our trip planning. His are the best videos out there that focus on sensible, actual, useful information. https://www.youtube.com/channel/UCucEU3ZqAjhVr2WMMKNpc6Q