Mt. Diablo offers a mixed bag of climbing: trad, top rope, and sport routes. There are some bouldering, but not at the major established climbing areas. Most of the climbing is on sandstone, which makes the sport bolts sketchy, and some of the trad routes are scary. It also makes for some fun smearing and edging moves everywhere. Almost all areas have a simple way to set up a toprope, though you should bring really long slings (20' +) for many of the anchors. There is an entry fee to the park.
Summit Trail Walnut Creek CA