Transportation around the cities and towns of Thailand is unusual. Taxis operate in major tourist destinations such as Bangkok, Chiang Mai and Phuket but are rarely found elsewhere. Taxis are legally required to be metered in Bangkok. However, taxis found waiting outside superior hotels may refuse to use their meter and instead quote fixed prices, which tend to be about double the metered rate. Avoid these illegal fixed-rate taxis by walking down to the street and hailing an ordinary taxi.
Taxis in Chiang Mai, Phuket, and Koh Samui do not use meters but quote fixed rates for all destinations. It's best to ask for advice at your hotel front desk or check with several taxi drivers before committing to any lengthy taxi ride. Make sure you agree on the price in advance. Taxis are also available for hire on an hourly or full-day basis.
By Taxi
Travel by Train
State Railway of Thailand (SRT) has a 4000-km network covering most of the country, from Chiang Mai in the north all the way to (and beyond) the Malaysian border in the south. Compared to buses, most trains are relatively slow, but safer. Point-to-point fares depend on the type (speed) of the train and the class of the carriage. There are three main classes:
First class (chan neung) 2-berth sleeping compartments with individually regulated air conditioning are available on some trains, but prices are sometimes matched by budget airfares.
Second class (chan song) is a good compromise, costing about the same as 1st class buses and with a comparable level of comfort. Some 2nd class trains are air-con, others aren't; air-con costs a little more. Second class sleeper berths are comfortable and good value, with the narrower upper 
bunks costing a little less than the wider lower bunks. Food and WCs are basic. 2nd class Express Railcar trains have reclining seats and refreshments are included in the fare; unlike all other Thai passenger trains, they can match buses for speed, but cannot carry bicycles.
Third class (chan saam) is the cheapest way to travel in Thailand, with virtually nominal fares, and can be great fun. Sometimes packed with tuk-tuk drivers heading home with a sack of rice and a bottle of cheap whisky for company, as a farang you're guaranteed to be the center of attention - quite enjoyable in small doses, but 10 hours of this might be a bit much. Some 3rd class 
trains have wooden seats, others are upholstered; some services can be pre-booked, others cannot; refreshments are available from hawkers who roam the aisles.
Pre-booking is recommended, especially for sleeper berths. Many travel agencies will spare you the trouble of travelling to the station to buy tickets for a service fee (often 100 baht/ticket), or you can reserve with SRT directly by e-mail at
passenger-ser@railway.co.th for a 200 baht/booking surcharge.
