The SO and I spent seven days in Portugal earlier this year. Most of it was spent in Lisbon, although we did take tours of some outer areas. As for recommendations, it is important to pinpoint what you expect to get out of the trip.
If it is beaches you want to visit, then just do some research on those along the coastline. We were there in late January, and the beaches were cold, blustery and rainy. Granted, it was not the opportune time to visit the shoreline, it’s worth investigating what the weather will be like when you are there. We visited Cabo da Roca, the western most part of Europe, although we didn’t make it down to the beach because of the weather.
A suggestion is to focus on absorbing some of the country’s culture. Its history and religious beliefs (Christian) are the main aspects. We took the train from Lisbon to Belem for a half a day’s meander around the area. As for a religious insight, Fatima is not to be missed.