the string cheese incident...anything live from the "on the road" albums or the new studio album one step closer is good...very mellow. their sound changes constantly, they play bluegrass, jams, folk, trip hop, blues, rock... and dylan. nothing beats bob dylan for mellowing out to by yourself. try blonde on blonde, highway 61 revisted, or any of the bootlegs series. or just the greatest hits. cant go wrong with dylan.
check out Matisyahu, Jack Johnson, or some Ben Harper for some new tunes to chill to. Matisyahu is fuckin awesome, Live at Stubbs album is the shit. i dont know if he has his studio album out yet, but King Without a Crown (live) is the shit so much better than the studio version.