Starting with the Goldmine trail is a great place to get a workout as you get steep hills to build hiking strength. On the other side of Goldmine Mountain is a series of trails over many more hills.
As the San Tan Mountains are as far south east as you can get and still be part of the Phoenix metro area. These trails have people on them everyday though they don't get any where close to the amount of traffic you find at Piestewa Peak or South Mountain.