If going to Ávila, you can skip Béjar. The Medieval walls aren’t much different. I found the town confusing to drive in and honestly, couldn’t wait to leave. Near Béjar is El Barco de Ávila. It has a castle one can walk around the exterior of and a nice Medieval bridge.
La Alberca and Mogarraz are great to visit and we thoroughly enjoyed visiting them. They are only a few miles from each other. Between Béjar and Plasencia, Hervás was nice to walk around although it has no must see sights. The Jewish area and Puente del Lugar were the highlights.
In that same area is Granadilla and its castle. The residents were forced to abandon the village when a nearby dam was created, but not allowed to return when it was known the waters were not going to flood it. The castle is only one tower but affords a good view of the area. One can walk along the walls and through the village that is now a school. Plan your trip because it closes for a few hours in the afternoon.
For a village with unique city walls, visit Galisteo. Unlike most town walls, its walls are made from river stone. One can walk the walls. There are no railings going up the stairs to the walls. There’s nothing special about the town itself.
If you’re a Saint Teresa of Ávila fan, her tomb is in Alba de Tormes at Convento y Basílica de la Anunciación, MM Carmelitas. There was an article on her today and findings from when her tomb was opened last year. It was an interesting read.
I agree that Zamora should be added to the list and to skip Valladolid. Further away is León and Puebla de Sanabria. Puebla de Sanabria has a nice small castle, an old church and village plaza. It’s nice to wander around.
In addition to Cáceres are Trujillo and Guadalupe. Guadalupe has the UNESCO monastery. Trujillo has the main plaza and large castle. Both may be too far away for a day trip.
If you’re short on time you could drop Ciudad Rodrigo. It has no wow sites. If you do make it there however, visit the Parador that is the old castle and climb to the top of the tower. It affords a great view of the surrounding countryside.
There is free parking in all the small towns and villages I mentioned, as well as Cáceres, Trujillo, and Plasencia, but you should look up the lots ahead of time.