There is one place I remember, passing through on my way to Cali. Maybe it was Saguaro National Forest. There was one spot just off the road where, with a little imagination, it looked as if the cacti were marching single file up a mountain. Since I was on my way to a new job and everything was locked up and boxed up, I never got the shot. I can't remember if it was closer to Phoenix or Tucson though. Maybe you can get down there for a day.