So,
You can very well use this opportunity to visit Tirupati Devasthanam to visit if you have faith for religious places. While coming or while returning.
another place is Arunachal Mountain and Raman Maharishi Ashram.
Chennai itself is very good place to enjoy, its beaches, and south Indian food,
Next...
more... is Madurai, Meenaksi Temple and its granduer, along with other temples
south most is Rameswaram, and nearby is KanyaKumari , both are nice place to watch and worship the sea.
I have also heard about a temple with 1000 pillars , but its town name is not sure.
Apart from this place, You have hill stations, Ooty, Kodaikanal.
Many private bus operators/tour operators are available. Just click the Parveentravels.com, and you get huge information, for small trip, long trip, chartered vehcle, hotel booking.
Many more places of interests are there but I have known this much.