I'm interested in travelling overland from Ubon Ratchathani to Trat, preferably avoiding Bangkok and, instead, by road or rail, cutting East and perhaps staying close to Cambodian border or stopping off to see Khao Yai National Park. Has anyone done this journey or know how easy it is to travel this route? Planning to do this sometime in January and would be very grateful for any info or intelligence (especially as there have been problems recently between Thai and Cambodians near border (Preahar Vihear).Many thanks.
I went to Chanthaburi from Prachinburi a few years back. The main terminal was in Sa Kaew and the bus took highway 319 which hugs the Cambodian border. It was a really nice, really slow trip.
I also found out recently that there is now a direct bus to Chanthaburi from Aranyaprathet. If you can get to Aran, you'll be able to get to Chanthaburi on this same highway without having to do much backtracking or wandering around.
If you have time and want to just putter from place to place, you can get there through a combination of buses or songthaews out of Si Saket, Surin, Buriram, Aran, Sa Kaew, Prakhon Chai, Ban Kruat, and Khorat.
Somtam's suggestion is the most direct. I think that the best thing about this route besides speed is the option of making a sidetrip to Phimai.
Buriram - Prakhan Chai and Ban Kruat give you the option of checking out Prasat Phanom Rung.