I have been to Mt. Diablo State Park many times and always enjoy it.
Wind Caves: The caves and rocks at Rock City are a favorite to climb, and my older son can climb them with adult assistance.
Hiking: You can drive all the way to the summit, but it's more fun to hike part of the way. There's one parking lot before the summit, Lower Summit Parking Lot, where you can take the Trail Through Time to Devil's Pulpit, followed by hiking up to the summit. Devil's Pulpit is a jagged rocky area that's not safe for kids but is safe for adults who climb it carefully. There's an unbelievable panoramic view from there and many other places on the mountain, especially when you look down from above the clouds. You feel like you're on top of the world.
The summit: It's very cold at the summit, so even if it's not cold on the way up, have a jacket to wear at the top. The summit is in the middle of a small visitor center that's build around it, so it's interesting to see a mountain jutting out of the top of a building. There are telescopes at the top that you can put coins in to use. I've also seen people hang-gliding near the mountain.
History: It's an interesting educational experience when you read the signs. You can learn about geology during the age of the dinosaurs. When I read more with my son, who loves dinosaurs, we found that Mount Diablo was under the ocean during the Jurassic and Cretaceous periods. There aren't any dinosaur fossils from the mountain, but it's an interesting fact that you're hiking where the ocean once was. It also has spiritual importance to Native Americans and is a California Registered Historical Landmark. There's an interesting scientific and human history behind it.
Camping: I went camping at Mt. Diablo once, and there wasn't anything particularly outstanding about the camping. It's still a great experience being in nature overnight for a few days not far from home if you live in the Bay Area. It also gives you more time to explore more trails day in and day out.
Snow: When it snows, I've seen the road blocked off at the Juniper campground parking lot area, where you can park and hike the rest of the way up. It's an enjoyable short hike walking in the snow!
Entrance Fee: the main entrance fee is $10.00 per car (Seniors 62 and over: $9.00 per car), so carpool if you can and make it an all day adventure!
