You can visit Lahaul Spiti in summer for 3-4 days. The place is also known by the name Himalayan Desert. You will get to see beautiful scenic beauty and I am sure you are going to love it. Also, you can prefer for snow trails camp if you are adventure buff and indulge yourself in adventurous games.
You can go to 1)Panchmari in Madhya Pradesh, it is a very beautiful place.
2) Ooty (South)
3) Mahabaleshwar (Maharashtra)
4) Matheran, Maharashtra. It is not exactly a hill stations but a very beautiful place.
5) Mount Abu, Rajasthan