Why don't you plan for Sikkim!? It's the best time to visit North Sikkim like Lachen-Lachun-Yumthang valley- Gyrudongmar lake- finish with gangtok. Or else plan for Uttarakhand.. It'll be full of snow both of the places: )
If you want visit to South India and enjoy the greenery you can visit to coorg, chikkamagaluru,munnar,ooty. or if you want to visit in North India I urge to visit Manali Shimla Darzeeling