Hmmmm, I don't think I took any off-Camino detours for Romanesque churches on this route. I did take a day to visit Valladollid, which I really enjoyed. The sculpture museum is in a Renaissance convent, and the church facade is stupendous Baroque, probably Plateresco, which is the special Spanish baroque. There is also a house where Cervantes reportedly lived, and a nice Gothic/romanesque church tower. And the Plaza Mayor is really pretty.
The castle in Manzanares is wonderful, it is supposedly the best example of Castilian XVI century military architecture. But it is right on route and easy to visit. Coca's castle is now dedicated to some sort of job center, I thnk, but Annie seems to have had the same experience I did and was able to walk around freely.
I didn't figure out how to get into the Romanesque church in Wamba, but as
@Magwood has confirmed, the main attraction inside is the bones chapel -- gruesome. There is a nice Romanesque church (I am thinking mainly of the apse) in Santervás, I think it is. And another very nice apse in Alcazarén, but those are all on camino.
Maybe my memory is failing, so Rachel if you can point me to those posts, I will see if I can figure out what I was talking about!