When I was 'in between jobs' here a few years back I bussed overnight to Hat Yai then caught the overnight sleeper train from Hat Yai to Bangkok. Comfortable trains and I liked the 'romance' of train travel but it was expensive compared to travelling on the bus. Buses in Thailand are really really cheap and very well equipped although sometimes the extremely cold aircon and thai dubs of english movies at earsplitting volumes can get to you. It's luck of the draw and generally the buses we were on were great ways to see the country.Over the course of a month we went overland from Sg through Isaan in the North East then right up through Chiang Mai to Chaing Rai using a combination of bus and train but mostly bus.
You can now get really cheap airfares in Thailand which are cheaper than the bus sometimes through the multitude of low cost carriers that have sprung up.
Dont plan anything, just take it as it happens....it really is the easiest country in the world to get around.
