India is overwhelming in the best way. The Golden Triangle (Delhi, Agra's Taj Mahal, Jaipur's forts and palaces) is a classic first itinerary. Varanasi on the Ganges offers one of the world's most intense spiritual experiences. Kerala's backwaters, Rajasthan's painted havelis, and Ladakh's Buddhist monasteries each represent a different India entirely.
Wildlife safaris in Ranthambore, Kanha, or Kaziranga for tigers and elephants; Goa's beaches and Portuguese architecture; Mumbai's film industry and street food; the Himalayas from Manali to Darjeeling — India is several lifetimes of travel in one country.