The Sundance Film Festival is always the most paradoxical of events, and this year's edition is shaping up as no exception.

This most important of American film festivals opens Thursday night in an enthusiastic town -- Park City, Utah -- that is unexpectedly small for an event of this significance. The fest prides itself on discovering the unknown, but its opening-night film, the British thriller "In Bruges," will be in theaters just a couple of weeks after the festival closes.

Sundance also celebrates independence, but it has become known as a site for celebrity swag. What do places like the Eco Lounge & Hotel ("the hippest Earth-friendly style suite") and the St. Ives Sensory Spa & Gallery have to do with independent film? And what sane purpose does it serve for Ray-Ban to give a Visionary Award to Quentin Tarantino, who likely has sunglasses of his own?

Everything gets bigger and bigger at Sundance, from the pioneering Queer Lounge, now located in a multilevel storefront on Main Street, to the number of features that apply to get in, which this year totaled just over 2,000 for the mere 32 slots (16 dramatic, 16 documentary) in the competition.

But the most intriguing Sundance paradox was articulated by festival director Geoffrey Gilmore when he said recently, "The films people talk about when they're going to the festival are not the ones they're talking about when they leave."

Still, because Sundance can launch a film (think "Shine" and "Little Miss Sunshine") like no other American festival, there is intense interest in what it will show. This is especially true for the dramatic competition, which traditionally features few names for seers to hang on to.

Among the films that do have names attached in varying capacities are "Sugar," the latest from the team that gave us "Half Nelson"; "The Mysteries of Pittsburgh," an adaptation of Michael Chabon's debut novel; and "Sunshine Cleaning," an evocative, unconventional drama from director Christine Jeffs ("Sylvia") featuring a vibrant performance by Amy Adams that not even the work she's done in "Enchanted" and "Junebug" prepares you for.

As always with Sundance, the documentary competition offers the most reliably involving films. This year things roughly break down into two categories, the personal and the societal. The best of the personal include:

* "Nerakhoon" (The Betrayal). The first film directed by the exceptional cinematographer Ellen Kuras, this decades-long story of how a Laotian family coped with life in the United States is both exquisitely beautiful and emotionally compelling.

* "Roman Polanski: Wanted and Desired." A powerful examination of the legal circumstances surrounding the director's decision to leave this country.

* "Trouble the Water." Part home movie, part reported documentary, this look at Hurricane Katrina and its aftermath shows us that disaster in ways we haven't seen before.

Equally strong are the docs that deal with societal problems. The best of these include:

* "Flow: For Love of Water." A lively and engaging look at a truly serious situation, the threats to the world's supply of drinkable water.

* "I.O.U.S.A." As it cautions us about the problems we are getting into with a national debt as big as the Ritz, this might be the most unexpectedly frightening movie in the festival.

* "Secrecy." The question of how much we should rely on methods inconsistent with our values is intelligently and elegantly handled.

A documentary unaccountably exiled to the non-competition Spectrum section is "The Linguists," a fascinating journey with two men who are the Indiana Joneses of language hunters, academics who go to obscure corners of the globe to find and preserve disappearing languages.

This documentary vigor extends to the shorts section. On the same Documentary Spotlight program are Lauren Greenfield's "kids + money," which features L.A. kids addicted to shopping, and "La Corona" (The Crown), an unexpected look at a beauty pageant behind the walls of Colombia's scariest women's prison.

"La Corona" would double-bill nicely with "Pageant," a documentary showing at rival festival Slamdance that takes us into the lives of contestants in the 34th annual Miss Gay America pageant.

"Pageant" points out that Slamdance, which is now established enough to insist it is "less and less the redheaded stepchild of Sundance and more of its own special, viable construct," has a knack for picking docs that are wackier and more human than the ones at Sundance.

This year those include "Spine Tingler! The William Castle Story," a loving tribute to the king of horror movie gimmickry and genial self-promotion, and "Circus Rosaire," a charming and affecting look at what today's show business economics are doing to a family that traces its circus roots back nine generations.

If things other than documentaries interest you, Sundance is happy to oblige, with films such as "Just Another Love Story," a nervy and stylish modern film noir from Denmark, and "U2 3D," a production that offers not just an up-close look at the music of the Irish band but also a sense of what it feels like to be present at the monster Latin American stadium concerts where this was filmed.

Sundance, to its credit, has also found room for something of value that is not so cutting edge, a version of the 2004 Broadway revival of "A Raisin in the Sun," the classic Lorraine Hansberry play, which won Tonys for Audra McDonald and Phylicia Rashad and also starred Sean Combs. This is apparently the first time that a broadcast network film (it will be shown on ABC) has been featured at Sundance, and it speaks well for the festival that the ground it is willing to break doesn't always have to be hip.

kenneth.turan@latimes.com