The paved path is family friendly. The singletrack is a bit more difficult but hugs the paved path. A family could easily split based on abilities.
The trail tread is mostly clay based and can be wet (closed) up until the middle of May. Once dry, this trail sheds water nicely and rides firm and fast.
Upper Mac is a fairly new mountain bike trail. It provides a moderate, flowing singletrack with some tight technical turns and fast sections. This trail runs in both directions - depending on the day of the week. The trail is quite a bit different as each direction has its own character.
The parking area and trailhead are located off of 84th Street, and the trail can be accessed either via the Upper Mac Connector from the parking lot or you can choose to ride up the paved path to the trailhead. You'll need to pass the trailhead information station and follow the path which leads to the sign designating entrance route based on the day of the week.
A wide paved path was recently added that connects Byron Road and 16th (Adams) Street for nearly two miles of casual riding, running, and walking. This is a prime trail and a must-do if you're in the area. There are a few spots you can bail to the paved path to shorten the length of the ride.