On the Lisbon to Pirto leg A must is Tomar to visit the World Heritage Convent do Christo , the Templars convent.
Coimbra with its famous medieval university and the world famous library.
If you have time, stay in each above mentioned towns an extra day.
Take a day or two to sightsee Porto and if you are in Barcelos , take An extra day and take the bus or train for a 20 kms long trip to Braga and visit the world heritage sanctuary Bom Jesus do Monte . A must too when you are in Portugal.and the City center of Braga is very nice . You will enjoy the day.
And do not forget to stay at
Casa da Fernanda, the best privat albergue on the entire Portuguese caminho.
From Barcelos about 18 kms on the waymarked caminho in the hamlet of Vitorino dos Piães.
Ponte de Lima is a nice town but if you start early from Fernandas about 9 o clock you will be about noon in Ponte de Lima and have time enough to see the compact center. No need to stay another day there.
Now I see you do the coastal.
I have done both the central and the coastal.
No places in particulair to stay an extra day .
Viana do Castelo is nice for one or two hours but then you have seen it.
Same with Caminha. Small towns nothing special.
Baiona has a nice fortress but also here within 2 hours you have seen the lot.
Vigo a big city but nice if you like shopping ....
South of Porto as I mentioned above Tomar and Coimbra are more interesting and Porto and Braga,.
Bom caminho