Hank Snow, Porter Wagoner, Charlie Walker, Charley Pride (his old stuff).
Also check out Martina McBride's album "Timeless". It's all old classics, old (maybe original) arrangements, and played on 1960's instruments and equipment. The first track on the album is Hank Williams "You Win Again", and before the introduction is over she's already hit her first homerun. The musicians are obviously having fun with it; you can here them occasionally channeling Floyd Cramer, Ernest Tubb, etc.