There are Tourist Authority of Thailand (TAT) offices in bigger towns in the region (though they’re not conveniently located). Check out www.tourismthailand.org, or call tel 1672 for assistance. In our travels, we have found 12Go’s (www.12go.asia/en) English-language website takes the hassle out of booking regional trains or buses, and it accepts credit cards.
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.