Well...
Phoeinx is 268...however, it takes 7hrs to get tehre from Vegas, because you have to take the slow US-93.
Los Angles on the other hand is 270 Miles... BUT it only takes 4hrs to get there becuase you cause use the straight shot I-15.
The Southern California Xterra Club looks to be your closest. ALthough, Arizona Xterra club always welcomes you to any activites that we do. We fairly often drive up to Flagstaff and do activites there, so when we do those you may be interested in comming down and hanging out with us. Check out our Section of the XOC, and dont' be shy.