I think you should visit gangtok, shillong, manipur, these cities are close to each other and located to high altitude . you will enjoy the hilly areas of these cities.... happy traveling??
Hey Aftab, If you are in or near Guwahati then there are multiple options you can choose : 1)Gangtok (Nathula pass,North Sikkim) 2)Tawang (Arunachal Pradesh) 3)Shillong( Cherrapunji,Dawki) 4)Imphal