Visit Bisti Badlands if you get the chance. Perhaps not the greatest hiking but fabulous rock formations. Not very well known so there's rarely anyone else around. More details here.
Caution: after rain the mud is slicker than snot, I was skating all over the place - but you all know how I am at keeping my feet on the slippery stuff.
Of course, had they not renamed it you could also have driven on Route 666 while you were there.