Where you want to Go in North East. If you want to Explore Assam, Meghalaya nd Arunachal Pradesh then Guwahati is your base for NE Tour. As From Guwahati you can plan Meghalaya tour ( Shillong, Cherrapunjie, Dowki) Or Arunachal Pradesh ( Tawang, Bomdila)
U can go to gangtok, lachung, peeling , darjiling ,Marik , kalimpong, lachen,yumthang valley, zero point . from Siliguri u can hire taxi. all these places are very beautiful