When traveling by train in Thailand, if you want to enjoy the scenery, prefer 3rd class cars, which are certainly less comfortable and not air-conditioned but without windows. A good thing when you know that the windows in the upper classes are often dirty and do not allow you to see clearly outside. The other great interest of traveling by train in Thailand is the contact with the locals. The vast majority of passengers are Thai and it is not uncommon for them to offer to share with fruit or other foods they have purchased. You often meet nice people on Thai trains even if communication is not always easy. For those who really want to know the country and the inhabitants, it is an experience to be lived. And the ballet of vendors in 3rd class cars (and only 3rd calss cars) with their platters of kebabs, chicken thighs, bottles, drinks, cashews, rice dishes... is fun to watch and personnally i prefer to buy from them than getting my meal from the Thai Train Company. No need for a dining car, they bring you everything on a tray! Everything is sold at 10, 20 or 30 baht. In 1st and 2nd class, depending on the length of your trip, you have one or more meals included in the price of the ticket and no street vendors but one hostess per wagon.
Be careful, before getting on a train in Thailand, make sure that it is yours, it may very well arrive exactly at the time yours is scheduled but that does not always mean that it is tyour train. The punctuality of the trains is quite relative here. In all the stations of cities frequented by tourists, you have a Tourist Police office which will inform you. Otherwise, ask the other passengers or the SRT officer on the platform if this is the right train by showing your ticket. You can also try to speak to them in Thai. This train goes to Chiang Mai, for example, is said: rod faï nee paï tee Chiang Mai maï khrap ? (this train goes to Chiang Mai, right?). Replace khrap with kha if you are woman and Chiang Mai with the name of the city you are going to. Note that it is generally not necessary to book your seats in advance except for the berths in the night trains (best to book at least 15 days in advance) and that it is preferable to do it a bit advance for Super Express trains (use the search tool). On the other hand, on long journeys (more than 1h30), book in advance at the station or on the internet (via SRT official website or 12go website) to make sure you have a seat. If you are leaving from the city where the train starts, you should be fine but if you take it on the way, you may have to do all or part of the trip standing up because in 3rd class, tickets are always sold regardless of the number of seats. Sometimes, it is better to pay the few euros in addition to have a booked seat... My advice: at least try to buy your train ticket at least at the station the day before for the next day. It's more expensive than the same day but at least you will get your seat allocated. Be careful, you cannot go everywhere by train in Thailand, Phuket for example, a major tourist destination does not have a train station.
The atmosphere of night trains in Thailand with their nightclub car is truly amazing ! It is often a memorable trip though you can't enjoy the landscape when it's dark of course. It is best to book your sleepers in advance at the station or via websites like 12go.asia.
If you prefer to organize your trip in advance, you can book your train tickets to travel in Thailand ahead. You can book online on the website 12go that we tested and validated. Advance booking is especially recommended for sleepers in night trains but can also be good for some super express trains.