Seven days covers Bangkok plus the islands. Fourteen days is the comfortable minimum for Bangkok, Chiang Mai, the Andaman, and Ayutthaya or Pai without treating airports as the holiday.
7 days: Bangkok and the islands
Spend three nights in Bangkok (Wat Pho, Wat Arun, Grand Palace, one Yaowarat evening — see the 18 best things to do in Bangkok). Then four nights on Phuket or Krabi — one beach, one temple or cape, and one boat day (Phi Phi or Railay). Fly south; the bus-and-ferry combo costs a full day. Book both rooms and internal flights early for December and January.
10 days: classic circuit
The route most first-timers from India actually take: Bangkok (3 nights) → Chiang Mai (2 nights) → Phuket or Krabi (4 nights) plus a Phi Phi or Railay day (see the 16 best things to do in Phuket, 12 best places to visit in Phuket, Best Time to Visit Phuket, 10 best places to visit in Krabi, and Best Time to Visit Krabi). Internal flights (Bangkok–Chiang Mai, Chiang Mai–Phuket/Krabi) take about an hour each. This is the better first trip if you want temples, the north, and the Andaman without rushing Pai.
14 days: grand tour
Keep the 10-day core, then add Ayutthaya as a Bangkok day, two nights in Pai from Chiang Mai, or Koh Lanta after Krabi. Use flights for the long hops; long-tails for the limestone. A car is not useful in Bangkok; a scooter on the islands is optional and only if you already ride. Do not mix Andaman and Gulf islands on a first 14-day trip — the seasons disagree.
Build a custom version in minutes with the LokaTours trip planner. Pair the days with the 15 must-visit places in Thailand, the 20 best things to do in Thailand, and Best Time to Visit Thailand.