Pifka, I know Gautam can provide more information on India than us 'temporary' tourists, but I can provide some perspective as an "outsider" if you will.
My travel to India only included the north from Delhi down to Shekhawati, Jaipur, Ranthambore, Rajasthan, Bharatpur, Agra, Jhansi, Khajuraho, Varanasi, and Sarnath. If you're going to hit any of those spots, ask away. c.i.