Out of Denver, Yazoo's up on Broadway, Champa and 22nd is by far the best dry I've ever had. Heavily smoked. Place is a bit weird to go into, but well worth it. Moreso on the way to the Great Divide brewery just a block or two away.
Sam Taylor's (Cherry St in Cherry Creek) used to be a favorite, but the ribs at least have gone a bit downhill over the last few years.