Trip starts from NJP(train) or Bagdogda(flight). It was a 4-5 hour journey to Gangtok. The roads are really nice. I am sure you will enjoy your ride through the Sevok road which is a long stretch of road with teak plantations on both sides. After that starts the winding roads as you climb up alongside river Tista. On your right you will see the huge Coronation bridge which stands as a huge arch over the river valley. You will cross a checkpost at Rongpo which is the entry to Sikkim. In another hour from there you would reach Gangtok.
Modes of transport: Book a car , Share jeep, Bus. (4-5 hours journey)
You can rest on that day and roam about on MG road. Do some shopping at Lal market and enjoy steaming momos.