The name says a lot: Greensky Bluegrass. So sky is the limit when floating on clouds of intricate melodies, strings, and more strings. We're talking banjo, mandolin, dobro, upright bass, and acoustic guitar with earnest, laid-back vocals. Ten-minute jams speak to the band's need to take the music higher; even raggy horns and fuzz guitar find their way into the grooves sometimes. Greensky's vision has a broader apeal than most country: While hippie dancers love the Dead vibe, musicians dig the instrumental mastery. And world-class new-grass vet Sam Bush will guest on mandolin this Friday, too.