Though Phoenix mountains never reach higher than the 4000 range especially Esterella, they have great hikes, that can be ball busters. some of the hardest trails I ever walked up are the Phoenix surrounding mountains. The rockies where easier for me than these mountains.
Papago is got to be the strangest place I been to in awhile besides the Chircuahua. I call this park Dinosaur DO-DO. The caves is a wonderland for exploring. forget the trail, and just play like a child. I made it to the top several times, and is a easy walk up, but if you are afraid of heights then maybe you should stay on the bottom part. lol. Though small in size it has a punch of enjoyment to offer.
South Mountain in the summer heat is a freakin killer, but I have hiked many of the trail and all the new ones of Ahwatukee most people never even heard of. I live right at the base of South mountain, and so I walk it a lot. The Ahwatukee side is almost always alone on the trails. Gila trail is a great hike to Telegraph pass.
Pist. - Squaw peak is surely a ball buster if you are not ready for it. only one mile to the top, but you will think you hiked 10 before it is over, but the view is a great one from up there. I feel so out of shape when 70 year olds are passing me 3 times on this trail. I just dont get it, how they are doing it so quickly. I am surely humbled by the Phoenix Hiking Machines that trek this mountain daily.
Camelback - is surely the Knee buster hill. I have hiked this mountain once the whole way, starting from the golf course and ending up on the other side. This one put me out of commission for 2 months, since I had 2 knees surgeries and had my cartilage removed. It is an easy trail but again if you are not ready for it, it can be a killer trail. I hear all the time people dying on this trail, if that is true or not, i am not sure, heck I am an eastern Smoky Mt man who just moved here.
I havent done North Mountain, Usery, or Esterella so if you wanna go with me and you walk slow, then look me up, I am ready. Plus I am ready to bike all the Canal trails in Phoenix as well, since it is easier on my knees.