Luk thung is often characterized as Thai country music, which is both accurate and misleading. It's accurate in that, yes, luk thung is mostly created and consumed by folks from rural backgrounds, and its lyrics reflect their concerns—the love left at home, the joys of rural cooking, the shock of moving to the city and discovering that your new urban flame is a he rather than a she, etc.
It's misleading, though, in that luk thung doesn't sound anything like country music. It sounds like film music exotica. Also garage rock. And like J-pop and Bollywood and AM radio balladry. And like hip-hop. In other words, and very much unlike American country, luk thung is almost pathologically omnivorous.
It's also mostly unavailable in the U.S. Still, with a little effort, and through the magic of online vendors like eThaiCD and thaimegamart.com, even non-Thai speakers like me can get hold of some recent releases. (Because I don't speak Thai, song-title translations here are provided by Jod Taywaditep, a Chicago native-Thai speaker who kindly offered to help out.)
A great place to start listening to luk thung is with Cathaleeya Marasri's Ruam Hit Pleng Dung. A 16-track greatest-hits collection by one of the most popular and respected Thai singers, it couldn't be much more stylistically varied. "Ta Tor Ta Fun Tor Fun" ("An Eye for an Eye, a Tooth for a Tooth") is shoulder-shrugging soul, with Cathaleeya's knowing vocals sliding over horns that sound like they could have come out of Memphis and an occasional gritty electric guitar. "Sao muang nont" ("Girl from Nontaburi"), on the other hand, is disco funk, with a smooth sax and cheesy keyboards contrasted against the singer's blistering quasi-rap.
Poifai Mallauporn's Muk Laew Krub is, to Western ears, even more unusual.vThe title track sounds like a backpack hip-hopper sucking helium while some sort of fractured carnival music plays in the background, courtesy of the strikingly enormous Thai mouth organ known as a khene. No other song quite reaches that level of inspired goofiness, and there are a couple of hard to take power ballads—but Poifai's vocals are never anything less than bizarre, and you do get to hear more of his spastic take on pop funk in tracks like "Sa Ra Aoy," or "Things That Rhyme With ‘Oy,'" a stream-of-consciousness rap in which, like the title says, all the lines end with "oy."
Tai Orratai's Morlum Dok Ya (Wildflower Morlum) is something else entirely. The mor lum of the title is a gritty regional style from the Isan region along the northern Laotian border—kind of like the blues to luk thung's country. Tai is a luk thung artist through and through; her mor lum is smoothed out and prettied up. I've seen purists express reservations, but to me it has the charm of an Emmylou Harris album, the distance from authenticity coming across as painfully sweet longing. "Tung Jai Luem" ("Make Myself Forget") is a riveting high point; the drums set down a slow, almost-waltz beat as a wind instrument trades choruses with Tai's pure voice. NPR would love it, but it's great even so.
For real mor lum, you can't do better than Siriporn Umpaipong's Bow Ruk See Dum (Black Ribbon of Love). I'm actually not sure when this came out, but it seems to have been re-released recently. In any case, Siriporn is one of the great modern practitioners of both luk thung and mor lum, and is known for her soulful, raspy vocals. The album is designed to evoke the singer's legendary live shows, and besides Siriporn's own singing, yelping, and rapping, the most exciting moments may be the shifts from song to song, as one mesmerizing groove flows seamlessly into the next.
Other luk thung artists I'd recommend include pop-tinged performers Kratae and Pamela Bowden (the latter of whom should have a new album out shortly), old-school singer Yui Yardyer, and founder of the genre Surapol Sombatjaroen. A good way to start investigating luk thung is YouTube; almost every track from every Thai album has a video, and a large percentage of these have found their way to the Internet. If you need more guidance than that, you can start at Made Loud. Happy listening!