Dear Anamika sorry for the late response
south sikkim - statue of guru padmasambhava
west sikkim Tashiding and the four sacred caves
North sikkim - Gurudongmar lake, lachen ,tso lahmo ,green lake ,kala phather ( you will get to play with snow during earl and late winters as well although u have to ask the diver to take ypu to this place as its not included in the package ) and if you love treaking and wi'd life you can get to hot spring which is completely in the wild tarum hot spring ask if intrested, lachung ,zero ,yumthang
East sikkim - nathula pass ,wild life concept zoo ,
all the above mentioned places are holy places