Tamil Nadu has many temple towns worth visiting. Some of the temple towns that you should consider visiting are: 1. Mahabalipuram 2. Tiruchirapally
3. Madurai 4. Kumbakonam 5. Rameshwaram
I guess kerala would be a very good destination for such trip. it has got very good greenery and serene enviromnet which can freshen up anyone's mind and soul.
Kodaikanal and pondicherry are beautiful places,scenic and away from the crowd plus the drive is absolutely amazing.For more offbeaten path,you can go to Pollachi.