@garebear +1 on Gregg Allman's version of "These Days," although I've always liked the original version by Jackson Browne just as much. However, I think the ultimate version is when Gregg and Jackson perform it together live at the "All My Friends" tribute concert for Gregg.
I heard that the only performers at that show who knew that Gregg was terminally ill were Jackson Browne and Don Was; thus, making that performance even more poignant.