This erstwhile princely domain of the hill tribes of Sikkim had developed into a great tourist attraction for many reasons. To meet the modern demands of comfort of the fast growing tourist influx has transformed the existing one/two stars hotels into luxury resorts with some big names opening up four and five star hotels as well. Mayfair Spa Resort and Casino a five star is a front runner and very popular. Almost as good are the four stars like royal plaza, Summit Hotels etc. Apart from these hotels you have umpteen numbers of fairly comfortable hotels which provide all the basic needs and meet the pocket size of even the lower middle class that is 1 to 2k/day. Even the 4 star hotel costs below 5k per day per room. The hotels provide transport on hire for visit to various sightseeing places like the Nathula pass, the monestries/gomphad and beautiful lakes in the higher reach which freeze during winters.
Gangtok can be visited all throughout the year, however, the temperature in December-February can go below freezing point while summers have an ideal weather. Being a hilly region, you never have to worry about it being too hot. The only season you have to be careful about is the monsoon when there could be heavy landslides and hence travelling to Gangtok should be avoided.
To reach Gangtok you can take a cab or bus from Siliguri railway station or Bagdogra airport. You can even take a helicopter from Bagdogra airport for Gangtok.
Accommodation is generally available throughout the year but it is advisable to make advance bookings so that you get a hotel of your choice.