I visited India last fall and wore long sleeve button down shirts or twinsets and trousers (a little nicer than khakis). The Indian women I met with at work were similarly attired, or wearing traditional sari outfits. Our company's executive women have generally worn pant suits and button down shirts from what I've seen and heard. Some additional guidance I received was to avoid anything too tight and not wear anything that shows your shoulders (outside of hotel spa/fitness centers).
That said, khakis and polo shirts are generally fine for weekends and lounging around at the hotel.
Good luck!