Westerners certainly have more of a love for trains than most of the locals in Thailand, the latter of whom consider such mode of transport as almost prehistoric - then again, I guess some of the trains operating actually are!
While tripping around Thailand though, it's almost a must, at least once, to experience the one-and-only Thai train. Take the Bangkok-Chiang Mai train, for example: even though the train does the journey much slower than the overnight bus, you won't have to tolerate blaring karaoke or sub-zero air-conditioning.
Instead, you could be having a lot of fun in the train's funky restaurant meeting locals and fellow travellers while enjoying a friendly game of cards and a chilled beer.
And instead of waking up in the morning to the sight of a six-lane motorway and countless petrol stations, you'll be relishing a beautiful sunrise from the heart of the Thai countryside.
If the North isn't your cup of tea, then head to Isaan, which definitely has one of the best routes in Thailand: Nakhon Ratchasima to Ubon Ratchathani.
source:http://www.dailyxpress.net/2008/03/15/travel/travel_655.php