You can pick up the path at various points, but one that is near a few of our recommended hotels is near the Hyatt Irvine (1/2 block south) off of Main Street. Look for the bridge and you'll find the path on the south side of the dry creek. It's a wide concrete slab route that goes for miles toward UC-Irvine. The path dips and rises under intersections. The easiest route to run is an out and back - mileage appears to be marked. But, there are also some interesting alternative routes that fork off the path. They will require some running along a few busy roads, but for example, a stretch that follows Campus Drive to Turtle Rock Drive is a popular route too.
Athletic-Minded Traveler, LLC, in no way guarantees the safety and/or condition of this run route as these public paths and ways are not within our control. You are advised to use reasonable and prudent efforts to ensure your personal safety and security. Use of this map/route is at your own risk.