The towns of Caminha and Vila Nova de Cerveira both have lots of history and lovely squares. They also both have large outdoor markets, Caminha on Wednesdays and Vila Nova de Cerveira on Saturdays. Ponte de Lima has a lot of charm and interest to offer and is perfect for a day trip as is Viana de Castelo which has great views from the top of the Monte de Santa Luiza which can be reached by the longest funicular railway in Portugal.
Cross over to Spain for some tapas or seafood or take the ferry from Caminha with your car. There is a Celtic settlement at the top of Santa Tecla hill which can be seen from the Portuguese coast.