Scott,
Recommendations always help but you'll find some of the most fun you'll have is finding these "reference" recordings on your own. Used vintage vinyl(well cleaned) is an inexpensive way to discover music you may never have tried. Without it, I wouldn't have a clue about how good bands like Ozark Mountain Daredevils can sound.(ESP. Men From Earth, but any of theirs really). Anything by Ry Cooder. Ever hear of BW Stenenson? Me neither, but a $4 copy of his album, My Maria is one of the better sounding records I' ve found recently. Many of your favorites won't be anything you would have expected or got on recommendation. Enjoy the hunt.