Thank you cdnyul - checked it out and it certainly is central. It's just a bit expensive for us and we'd have to pay for parking on top. I don't mind walking or bussing from where we have booked and I think we'd have quieter nights there too.

Our itinerary from Jerez to Barcelona is coming together quite well, (thanks to everyone for lots of help), although we are trying to stay flexible about the details at this stage, waiting to incorporate any more excellent advice!
How amazing to find there is a festival in Zaragoza right at the time we planned to be there anyway! Thanks rialtogrl!
At this stage we have four nights after Zaragoza before we return our car to Barcelona airport and fly home on 17th October.
I think we'd like to settle in somewhere gorgeous (of course) and not too touristy - somewhere that is an easy drive to Barcelona airport on that last day (we don't leave until the evening) and which gives us the opportunity to make a few trips out to visit other lovely villages/beaches etc... we really should rest up a bit before the long long flight back to Australia especially since we are off to Japan two weeks later... whee!
We've been to Barcelona before and also north to Girona and Figueres so we are thinking perhaps the southern part might be good?? Thoughts?

Teruel/Albarracin.

Tarragona! From Tarragona, you can visit lots of places. Poblet, Montblanc, the Priorat wine region, Siurana, Sitges, the list goes on. And Tarragona itself is a wonderful little city with lots to do and see.

The Delta d'Ebre is also a wonderful place to visit. Tortosa has a great parador.

Thanks cdnyul and rialtogrl - some lovely ideas. Tell me more about Terragona. We have concerns about towns that really revolve around tourists and are full of tourist orientated food options etc... Is it likely to be still crowded with foreigners in mid October? Is there somewhere authentic to stay nearby or has everything near the coast been overrun. I know I might be being a bit harsh about tourists, being one myself, but we really do like to see the real Spain.

There should not be that many tourists in Tarragona in mid October. I would stay IN Tarragona or on the Via Augusta close enough to walk to the old part of town. You need to find a hotel with parking. Just avoid eating or drinking in Placa de la Font, or anything in the old town that screams "tourist" and you will avoid the "tourist eating."

The history of the place is both Roman and medieval. There are lots of great places to relax with a drink, there is great food, and there is an all-around good vibe.

There is a recently restored mercato, views of the Mediterranean, and castellers (though if you want to see castellers you might have to go to the town of El Vendrell that weekend.)

They have a good website -
https://www.tarragonaturisme.cat/en

From there, you can visit many places, it is a very good base as I mentioned above. And its maybe an hour to the Barcelona airport.