I'm not quite an expert on Chennai, but I did a 3 night stay at the Park Sheraton recently and it was very nice. There is a fantastic southern Indian restaurant in the back of the lobby. If you are Platinum you should get loads of free food and drinks in your room as an amenity. Good location IMHO.

However at most all the Sheratons in India, you have to scrutinize the bill for mistakes and overcharges. Also save the bill in case you don't receive your Starpoints later on.