A good friend of mine is getting married in Chennai next April, and odds are high that I'll be stretching out the trip so I can go poking around in southern India for a week or so. To set the baseline here, I've been to DEL umpteen times and traveled around northern India quite a bit (Agra Vrindavan Haridwar Jaipur Jodhpur Dharamsala Amritsar...), but have never set foot elsewhere in the country, so I'd like to see the sides of India that I haven't seen yet.

Iteration A of the plan is Chennai-Pondicherry/Auroville-Madurai-X, where X is a city with direct flights back to Singapore, namely one of Trichy, Trivandrum, Cochin or Chennai. Based on this and this thread, it sounds like the "Kerala backwater experience" is a must-do. Anything else I'm missing? Any restaurant/eatery/stall recommendations are also welcome, I love south Indian food ^