On the recommendation of a friend I decided to take a lazy Saturday trip to the top of Mt Diablo, a tall peak not terribly far from the bay area. I was assured that it was "beautiful" and also "gorgeous." I was not disappointed.
The roads up to the top of Mt Diablo are small, winding, and full of bicyclists. Don't plan to race to the top. For one thing, this trip is much more about the drive than the destination. For another, it's simply unsafe to pass for large portions of the trip. Take my advice, and take the warning signs seriously. The views on the way up are just as good as the views from the top and neither are improved by having struck a passing cyclist to get there.
There's a visitor's center at the peak built into what, if I understood the plaques correctly, was once basically a lighthouse but for airplanes. The light is still up there, and they apparently turn it on once a year in honor of Pearl Harbor.
To be useful for guiding planes away from the mountain the light needed to be slightly taller than the summit, and so the whole building is built around it. This provides the interesting and possibly unique experience of standing on the very peak of the mountain which was left exposed within the building for exactly that purpose.
Somewhere along the route between home and the parking lot something came loose from the bottom of the Jeep. Fortunately there was just barely enough signal to place a call to a friend who knows about them who was able to advise me, and the ranger station was able to provide the necessary zip tie to kick that can down the road, so I wasn't left stranded.
The trip back down the mountain is similar to the trip up, but with more trying not to hit the cars that have decided not to obey the warning signs. I don't know why people are in such a rush to get to the top. Yes, it's beautiful up there. It's beautiful the whole way there. It's okay. They're not going to run out of beautiful while you're waiting for a safe chance to pass.
If you find yourself in the East Bay some time, take a morning and visit Mt Diablo. You won't be disappointed.