Well I've only been down there once in my Jeep so far, so I haven't explored much. I went down there in my Daewoo, drove the refuge, almost got stuck, broke down, came home, bought a Jeep, haha. I've driven around the East side of the steens, to Mickey Basin, as well as the White Horse Ranch road, and the Steens Mountain Loop several times but I'm looking for a less "maintained" network of roads. None of the dozens of maps I have show the small off-shoot roads... I suppose I should get a GPS :P
The wild horses are beautiful... it's a pretty amazing to see them out in the wild
They're extremely skittish though, so keep a distance in order to view them effectively.