Two weeks is the right amount of time to do the south coast properly and connect it with a safari or a few days in the hill country. You are not rushing, you are not missing the things that require a detour, and you leave having understood what the coast is actually like rather than having seen its surface.
Days 1 and 2: Galle. Arrive and settle in. One morning for the fort in depth, one afternoon for Jungle Beach in Unawatuna. Two nights. Eat well. Galle has the best restaurant concentration of any town on the coast.
Days 3 and 4: Ahangama. Move 15 minutes east. Two nights. Kabalana Beach, the cafe scene, the stilt fishermen in the early morning. A slower version of the coast than Weligama, worth experiencing before you hit the busier bay.
Days 5, 6 and 7: Weligama. Three nights in the centre of the coast. Day trip to Mirissa on one day, early morning for Coconut Tree Hill and a swim near Parrot Rock. Day trip to Polhena on another day, two hours snorkelling in the turtle lagoon. Third day on the Weligama bay itself, a surf lesson if you want one.
Day 8: Hiriketiya. Move east, about 30 minutes from Weligama. Spend the rest of the day settling in and being slow. The bay, the cafes, the evening. Hiriketiya has a pace that takes a day to properly inhabit.
Day 9: Hiriketiya. A full day. Surf if you surf, swim if you swim, sit at a cafe with good coffee if you do neither. Visit Dickwella town in the morning to see the Wevurukannala Vihara and the local market. Take a tuk-tuk to the Hummanaya Blowhole in the afternoon.
Day 10: Tangalle. About 30 minutes east of Hiriketiya. A wild long beach, a different character from the busier surf towns. Spend the afternoon walking the coast. Stay one night.
Days 11 and 12: Tissamaharama and Yala. Move east to Tissa. Early morning safari at Yala National Park on day 12. Yala has the highest density of wild leopards in the world. Sightings are not guaranteed but the park is genuinely exceptional. Two nights in Tissa, one afternoon for the Tissa Wewa lake and the bird life there.
Day 13: Drive or take transport back west along the coast toward Galle or directly to Colombo. Or, if you want the hill country connection, head north from Tissa toward Ella. The drive from Tissa to Ella takes around two and a half hours. Ella is covered in a separate guide, but if you have an extra day or two before your flight, the train from Ella or Haputale through the tea country back toward Colombo is one of the great train journeys of the region.
Day 14: Final day. If heading back from Galle, stay one final night and take a morning taxi to Colombo airport, around one and a half to two hours. If heading from Tissa to Ella and then Colombo, the timing needs a separate plan. We cover the Ella to south coast route, and the reverse, in a dedicated guide.
Two weeks done right means you have covered Galle, Ahangama, Weligama, Mirissa, Hiriketiya, Tangalle, and Yala. That is the full south coast, properly. Most people who do this come back.