Rockledge Park and Cedar Hill State Park 

Rockledge Park starts in Grapevine (a Dallas suburb), and runs about nine miles along the north shore of Lake Grapevine through Murrel Park to some other park, whose name escapes me. The other trail is in Cedar Hill State Park, in Cedar Hill (another Dallas suburb), and it has loops of 10 - 11 mile, 7 miles, and, I think, 4 or 5 miles.

Both of these trails are primarily mountain bike trails, but I've run on them both some, without any problems. The Lake Grapevine trail is home to the Rockledge Rumble, a 25K/50K held in November.

Mike Ahearn