Darjeeling is located on the east part of Himalayas called as queen of hills which is filled with abundant nature to explore. Gangtok capital city of Sikkim which faces Mt.Kanchenjunga is filled with rhododendrons, natural beauty and some peaks that are purely mesmerising. Meghalaya called as abode of the clouds, with Shillong as it’s capital is the best climatic, nature beautiful spot of North east. My advice would be Darjeeling or Meghalaya. From Darjeeling Gangtok is 3 hours away. So while visiting Darjeeling you could cover Gangtok as well.