The Phoenix Mountain Preserve is my favorite place in the valley to hike or trail run. There are miles and miles of trails for the beginning hiker to the advanced. You can choose a hike with decent elevation or you can choose a hike that is fairly flat and perfect for running or biking. The trails are well marked and easy to follow, though be sure to know which trail you are on, because it is easy to veer onto another trail and get very lost (I have done it). There are multiple entrances to different trailheads that are miles apart, so it is fun to explore new routes and catch new views each time.
One of the best things about the preserve is that it never gets too crowded like Camelback or Squaw Peak. There are plenty of people out hiking, but the paths never get overcrowded and you don't have to dodge people or battle for position. It is dog friendly as well, which is nice since the other mountains have banned pets due to foot traffic. While there is always the chance of getting hurt on any outdoor hike or adventure, the Phoenix Mountain Preserve is much safer than the other mountain hikes because it isn't as steep or as rocky.
If I head out for a hike or a trail run this is normally where I go. It is beautiful, has miles of different trails, and never overcrowded!