While I haven't seen a rattler on the trail, I did see a Gila Monster 
> once -
  

Now THAT was a treat, wasn't it!
  I was mad at my hubby, took the truck out and did some back roads and 
there in the middle of the road was a Gila Monster!  I stopped, got out 
and just admired him!  Didn't have the camera! UGH!
  
I just saw a gila monster on the 96 Ranch Road about a week ago while out scouting for camp sites with AJ.JR.   It was crossing the road and we stopped, got out and took a few photos as it clambered off into the bushes.  I got too close and he bit my finger!  AJ.JR-- not the gila monster (bwah-hah-hah-hah ;-) )

Now the only animal I am still looking to see in the Superstitions is 
the Miner's Cat (ringtail)!
Since the ringtail cat is nocturnal, chances are slim for spotting one unless you do a lot of hiking at night. The last time I saw one was at Reavis Ranch during the fall when the orchard was loaded with apples.  We snuck down to the orchard after dark with our flashlights and just shined the various critters that were out there; raccoons, deer and, in this instance, a ringtail cat. Very cool. 

Another critter that would be cool to see is the coatimundi.

As for rattlesnakes, they are a beautiful creature-- in their own way.  I still don't like them, though, and try to steer clear of them when I see them.   I've seen my share and have come close to stepping on them a couple times.  Even almost sat on one once.   The thing is, for every one you see, there are probably a handful that you walked by and _didn't_ see.  Those are the ones I worry about.

I've heard that they can only strike about their own length, so as long as
you are outside of that range, you should be alright.
I had heard they could strike up to 2/3 of their own body length.  But, irregardless, the problem with that theory is, unless you grab them and stretch them out, you don't know how long their body is.  ;-) If they are already stretched out, then they can't strike very far anyway, until they recoil.

-- Sprocket