The wait is over, I finally reached the summit of Mount Diablo after moving to the bay area over two months ago. The view was amazing, perhaps one of the best I've ever seen! I really didn't want to come back down, so I spent some time in the observatory and hiked the Mary Bowerman trail, then came down an alternate route (Juniper to Summit trail).
For as close to a major city as Mount Diablo State Park is, there's really very little information about the trails other than a vague state park map from their brochure and a few blogs. I purchased a topographic map and plan to update the site with more information.
average hiking speed 2.85 mph
WARNING! Hiking and outdoor related sports can be dangerous. Be responsible and prepare for the trip. Study the area you are entering and plan accordingly. Dress for the current and unexpected weather changes. Take plenty of water. Never go alone. Make an itinerary with your plan(s), route(s), destination(s) and expected return time. Give your itinerary to trusted family and/or friends.