Morning: Visit the Shore Temple, a UNESCO World Heritage Site. The temple has three shrines, and you can see intricate carvings on the walls. Next, head to the Pancha Rathas, a group of five monolithic temples shaped like chariots.
Afternoon: Visit the Mahabalipuram Beach, where you can relax, build sandcastles, and play beach games with your family. You can also try some local street food at the beachside shacks.
Evening: Visit the Mahabalipuram Dance Festival (Dec-Jan), where you can watch classical Indian dance performances by renowned artists under the open sky.
Morning: Visit the Vandalur Zoo, which is home to over 170 species of animals, including tigers, lions, elephants, and giraffes. You can take a tour of the zoo on a battery-operated vehicle.
Afternoon: Head to the MGM Dizzee World, an amusement park with rides, water slides, and games for all ages. You can also have lunch at one of the park's restaurants.
Evening: Visit the Arignar Anna Zoological Park, which is also known as the Vandalur Zoo. You can see more animals and learn about their natural habitats.
If you have more time, you can consider visiting the Marina Beach, which is the second-longest urban beach in the world. You can also take a trip to the Guindy National Park, which has a variety of flora and fauna.
For a side trip, you can visit Kanchipuram, which is known for its silk sarees and ancient temples.
To maximize your fun, you can try some local street food and shop for souvenirs at the Mahabalipuram Bazaar. You can also take a boat ride at the Vandalur Zoo or watch a 3D movie at MGM Dizzee World.
For further suggestions, you can contact me or visit the booking website for more information on hotels and flights.