Nice and easy does it for Wilco this time

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.