Being regarded as America's most important rock-and-roll band must get overwhelming after a while.

Sure, Jeff Tweedy asked for it, with a series of albums that telegraphed Wilco's artistic seriousness, from the double-disc Being There in 1996 to the avant-noise experiments on A Ghost Is Born in 2004. But on Sky Blue Sky (Nonesuch ***), the Chicago sextet's sixth album, Tweedy sounds relieved not to have to worry about his reputation anymore.

Instead of coming off like an art project - a weakness of both the migraine-inspired A Ghost Is Born and its ballyhooed predecessor, 2002's Yankee Hotel Foxtrot - Sky Blue Sky is content with the sound of five musicians standing around a room, enjoying playing music together.

Or more likely, that would be sitting around playing music. Because Sky Blue Sky is a surprisingly mellow enterprise, an easygoing affair that seduces with its prettiness.

Occasionally, songs such as "Impossible Germany" do rev themselves into a jam-band ramble, becoming an outlet for guitarist Nels Cline to showcase his improvisatory chops, Allman Brothers-style, that should fit right in when Wilco headlines the Bonnaroo Music Festival in Manchester, Tenn., next month. (So far, there's no Philadelphia date on the band's summer tour.)

And gentle ruminations like "You Are My Face" are spiced with a dash of power-chord strum-and-drang, as well as subtle "feedback" contributions from Jim O'Rourke, the noise-monger who was a key collaborator on Yankee and Ghost (but shows up on only two Sky songs).

But the good news about Sky is that it steadfastly refuses to get in its own way. That was an all-too-common problem over the last decade as Wilco filled the void left by the grunge implosion and became anointed as a next-generation version of the Band, that group of scruffy white guys who were obviously making music of momentous significance.

Not that Tweedy's standing as a restlessly creative soul is undeserved. From the orchestrated pop of Summerteeth to the poignancy of such tracks as "Ashes of American Flags" from Yankee, the songwriter has consistently shown the resolve to push himself beyond the boundaries of alt-country expectation established by Uncle Tupelo, the early '90s band he co-fronted along with Jay Farrar. Farrar is now the leader of Son Volt, which plays the Trocadero on Friday and recently released The Search, its best album in ages.

Uncle Tupelo's cover of the Carter Family's song "No Depression" inspired an Internet message board and then a magazine that became shorthand for the rootsy Americana sound that, it quickly became clear, felt like a flannel-shirt straitjacket to Tweedy.

So after debuting with 1995's A.M., Wilco was in a hurry to leave any traces of twang behind. With Sky, however, the group has circled back to its cozy, careworn beginnings. Tweedy has always been an effective-enough singer (albeit one with severely limited range) and an adequate lyricist, who exposed his limitations as a word man with the 2004 poetry collection Adult Head.

He excels, however, as a writer of exceedingly pretty songs, delivered with just the proper amount of soulful grit. This served the band particularly well on Mermaid Avenue, the 1998 collaboration (and 2000 sequel) with British rabble-rouser Billy Bragg, which paired music with lyrics written by Woody Guthrie. It remains the first Wilco disc I'd reach for in a pinch.

Perhaps it's because Tweedy has put his addiction to painkillers safely behind him, or maybe he feels he no longer needs to prove his band's artistic worth. But Sky Blue Sky is the least anxiety-ridden Wilco record so far, and it gathers together a consistently melodic set of songs, from the sweetly earnest plea "Please Be Patient With Me" and lonely man's blues "Hate It Here" to the shimmering title track, which reasons "I survived, that should be good enough for now."

Rather than striving to be daring, Sky Blue Sky is deeply relaxed and comfortable in its own skin, and that's plenty good enough for now.

nolead begins Gretchen Wilson
nolead ends nolead begins One of the Boys
nolead ends nolead begins (Columbia ***)

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On her third album, the Redneck Woman puts a little less stress on the Redneck and a little more on the Woman.

To be sure, Gretchen Wilson delivers some typically brash, crowd-pleasing country rockers like "You Don't Have to Go Home" and "If You Want a Mother" ("I'll show you what a mother I can be"). It's telling, however, that the opener, "The Girl I Am," is not a fist-pumping anthem but rather a low-key, mid-tempo tune in which the singer admits to some frailties. That's followed by the first single, "Come to Bed," an aching plea for an end to domestic strife. It's also worth noting that the full line from the song that gives the album its title is "I'm more than just one of the boys."

It all represents a savvy move by Wilson. Besides underscoring her talents as a balladeer, One of the Boys lessens her risk of being stereotyped as a one-note artist, and positions her well for the long haul.

- Nick Cristiano

nolead begins Rufus Wainwright
nolead ends nolead begins Release the Stars
nolead ends nolead begins (Geffen ***)

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I'm not quite sure what Rufus Wainwright's doing wearing lederhosen emblazoned with his initials on the CD sleeve of Release the Stars. But the best of the lushly orchestrated songs on the fifth album by the Judy Garland-worshipping song-and-dance man make perfect sense. Wainwright - whose next project is writing an opera for the Metropolitan Opera - can't help going for baroque at every turn as he dresses up songs like the rocked-out "Between My Legs" (with Richard Thompson on guitar) and the soaring title cut with French horns and strings. But overflowing emotionalism is Wainwright's métier. While his weakness for pomp and circumstance would ruin a lesser talent, the 33-year-old songwriter is sufficiently disciplined as a composer to keep his grandiose arrangements from suffocating his sentiments. And that's true whether he's despairing about geopolitics ("I'm so tired of America," he sings in "Going to a Town") or getting bummed out about trying to hew to the straight and narrow in "Sanssouci." (Wainwright will be doing an in-store performance and signing at 2 p.m. Saturday at Borders in Bryn Mawr, 1149 Lancaster Ave.)

- D. D.

Contact music critic Dan DeLuca at 215-854-5628 or ddeluca@phillynews.com. Read his blog, In the Mix, at http://go.philly.com/inthemix.