The MtD Grand Loop series goes around the summit on all sides, in a roughly rectangular pattern, covering some of the loveliest areas of the mountain. A good starting point is the Juniper campground (GCM61W, at N 37° 52.611 W 121° 55.848), from which the Deer Flat trail heads north to Deer Flat, then on the Meridian Ridge trail to the Bald Ridge Trail, then south to Prospector's Gap; then south on the North Peak trail to Devil's Elbow, then uphill to the summit parking lot, then from the west end of the parking lot back to Juniper campground. The entire circuit is 10.5 km (6.5 miles), with 600 meters (1973 feet) total elevation gain. Today when I hiked the circuit, it took 2 hours 45 minutes hiking time (allow additional time for geocache searches and rest stops).
This cache is located near a large area that was destroyed by fire in May 2014. The area is only now starting to recover. There are great views to the east. Today as I was hiking, I could see the snowy crests of the Sierra Nevada mountains in the distance, while a blanket of fog covered most of the central valley, right up to the base of Mt. Diablo.
WATCH OUT FOR POISON OAK, BOTH ALONG THE TRAIL AND NEAR THE CACHE.