Bangkok to Chiang Mai
The overnight sleeper is the classic: 13 hours, a proper bed in first class, and breakfast as the train comes through the hills. Book 60 days ahead on the State Railway site; second class is fine, first is better.
Bangkok to Ayutthaya
Ninety minutes in third class for a few baht. Hard seats, open windows, and the most fun you can have for 20 baht. Go early and come back by road.
Kanchanaburi and the Death Railway
The line over the Tham Krasae viaduct is the scenic section; sit on the right side going west. Combine with Hellfire Pass on the same day.
Practical
Trains are rarely full outside holidays, but sleepers sell out. Bring water and snacks; the food on board is basic. Third class is not air-conditioned — fine in the cool season, punishing in April.
