12Go Asia is an excellent option to book transport tickets in Thailand.
Read the post Getting around Bangkok.
You will find very practical information about the subway MRT and the BTS Skytrain, transfers with Suvarnabhumi and Don Mueang international airports, the Tourist bus, public transport on the Chao Phraya River and on the Saen Saep Canal.
Some airlines such as Nok Air offer tickets combined with ferry and/or bus to access the islands and beach destinations on both coasts.
Revise the airline’s policy on baggage restrictions, especially with low-cost companies.
For short distances the Local and Express buses are sufficient. Cheap but slow and sometimes full of people.
The buses of the Second Class have air conditioning but do not follow the most direct route and have quite a few stops.
Long-distance trips are usually made at night and often take more than seven or eight hours, which is why it is essential to take into account the conditions of the trip.
It is advisable to book in First Class to make the direct route to the destination with the least number of stops.
VIP buses offer besides water and a simple meal, include entertainment onboard and a rest stop. In the S-VIP the number of seats is limited to 24, with ample room between seats and three rows instead of the usual four, very comfortable for long trips.
Bangkok bus terminals:
– East Terminal: Ekkamai Station of the BTS Skytrain (Sukhumvit Road).
– North, Northeast and Central Terminal (Mo Chit): Approach to the station by the BTS Skytrain (Mo Chit station) or the MRT (Chatuchak or Kamphaeng Phet stations).
Then take a taxi to the bus station or use the city buses, numbers 96, 104, 134, 136, 138, 145, 517 or A1. Check that you are in the right direction.
– South Terminal: Mai Tai Sai Station of the BTS Skytrain (Boromratchchonnani Road) and then take a taxi.
Commuter trains are less practical except to go from Bangkok to Ayutthaya and/or Lopburi.
For long-distance trips, it is highly recommended to book bunk beds in first or second class, in first-class the compartment is private for two beds while in the second one curtains are used to isolate the personal room of each of the four berths. They have a departure at sunset, from 6 in the afternoon.
Ferry & Catamaran
As with airlines, ferry companies increasingly offer combined bus/train and boat tickets, so links are guaranteed, or almost.
Get updated information from the following websites.