I went to Bhutan in December last year. Our trip duration was 12N/13D (Including Train Travel). Total trip cost was 15,500 INR. This was our Bhutan Itinerary:
Day 1 (24th December, Monday): Reach Phuentsholing by morning, Get your Entry Permit and leave for Thimphu by shared cab at 11 AM. Reach Thimphu at 5 PM
Day 2 (25th December, Tuesday): Visit to Thimphu Dzong, Museums (Postal Museum & Folklore Heritage Museum), Archery Tournament, Stay at Thimphu
Day 3 (26th December, Wednesday): Entry Pass extension & Restricted Area Entry Pass Approval, Visit to Textile Museum, Travel from Thimphu to Khuruthang by shared cab, Visit to Dochula Pass and Chimi Lhakhang enroute, Stay at Khuruthang
Day 4 (27th December, Thursday): Visit Jigme Dorji National Park and Overnight stay in Khuruthang or jigme Dorji National Park.
Day 5 (28th December, Friday): Visit to Punakha Dzong & Suspension Bridge. After breakfast excursion to Chimi Lhakhang, situated on a hillock in the centre of the valley. It is dedicated to Lama Drukpa Kuenley, who in the late 15th century used humour, songs and outrageous behavior to dramatise his teachings and due to this also known as "Divine Madman".
Day 6 (29th December, Saturday): Visit Royal Botanical Garden - 45 minutes hike.Chime Lhakhang (Fertility Temple).Stroll through the valley in Punakha and wangdue.
Day 7 (30th December, Sunday): Bus travel from Punakha to Haa, Hiking & stay at Haa
Day 8 (31st December, Monday): Hiking in morning at Haa, Travel from Haa to Paro by booked cab, Visit to Chele La Pass en route, Stay at Paro
Day 9 (1st January,Tuesday): Hike to Tiger’s Nest Monastery (Tips), Visit to Paro Dzong & National Museum, Stay at Paro
Day 10 (2nd January,Wednesday): breakfast drive up the valley to view the ruins of Drukgyel Dzong. It was from here that the Bhutanese repelled several invading Tibetan armies during the 17th century. Nearby visit traditional Bhutanese Farm House which offers good insight into lifestyle of local people.Bus travel from Paro to Phuentsholing, Train from New Alipurduar Junction to Mumbai.
Trains:
While going, Guwahati Express (15645) [Lokhmanya Tilak terminus to New Alipurduar station]
While returning, Guwahati Express (15646)[New Alipurduar to Lokhmanya Tilak terminus]
List of Documents:
A duly filled form
Copy of Voter’s ID or Passport
An Itinerary on an A4 Sheet
Booked Hotel’s Voucher (It is mandatory to show hotel booking confirmation of at least one hotel in Thimphu/Paro)
Passport Size Photo
An Undertaking Letter (In case you are travelling solo)
Distance with Major Places in Bhutan
Phuentsholing to Thimphu: 164 kms
Phuentsholing to Paro: 160 kms