Sarandë is the end of the Albanian Riviera and the nearest thing the country has to a resort town. It sits on an open gulf of the Ionian Sea, 30 or so minutes by boat from Corfu, and it has more than 300 sunny days a year. The Greeks called the place Onchesmos, the Italians renamed it Porto Edda after Mussolini's daughter, and today it runs on summer tourism and a big Greek-speaking minority. What makes it a good base isn't the town. It's what lies within an hour: a UNESCO-listed ancient city, a lagoon, a blue spring, and one of the best-kept Ottoman towns in the Balkans.
Three days is the right length because the sights are spread out, not deep. Butrint takes a morning, Gjirokastër and the Blue Eye take a day, and Sarandë itself needs half a day, mostly for sunset. The honest part: this plan is built for November and the winter months. The sea is around 19°C, the beach clubs in Ksamil are shut, boats to the islets mostly stop running, and rain is frequent. Butrint, the castles and the spring are better for it, with far fewer people.
Day one is Sarandë, its ruins and Lëkurësi Castle at sunset. Day two is Butrint and Ksamil. Day three is the day trip to the Blue Eye and Gjirokastër. Start on a Tuesday, Wednesday or Thursday: the Gjirokastër castle is closed on Mondays and shuts early on Sundays in winter. If you're heading north afterwards, 5 days in Tirana is the natural next stop, and Albania has the wider picture.