Best destination in India would be Gulmarg, Sonmarg, Pahalgam, Nainitaal, Dalhousie, Mcleodganj. PS for the same budget, you can plan for Thailand or Bali as well. A little extra per head.
In the north, Meghalaya shillong is a less explored place. Arunachal pradesh is also a good option. Darjeeling Gangtok Dharamshala are also good options. Manali is too crowded.