In November, I spent a week travelling through Kerala with some friends — it was a great trip, though extremely rushed. I totally recommend it, but wouldn’t suggest you try and make it as hectic as we did: we spent a week going through Trivandrum, Alleppey, Periyar, Munnar and Kochi, and didn’t really see any of those places in any real depth.
In any case, go to Kerala! It’s beautiful. Hopefully my photos do some justice to it.