Nice places to car camp near Silicon Valley:

• Mount Madonna: Most ecologically diverse county park, with miles of great redwood and oak woodland hiking. It’s better to camp here in the spring or fall. The marine layer from the Pacific keeps the park’s campgrounds downright chilly in the summer, even if it’s in the high 90s in Silicon Valley. We went one July 4 weekend expecting a respite from the heat and came home a day early because we were tired of freezing our fannies off (it’s not like winter cold, but it’s nippy enough to be uncomfortable in the summer).
• Uvas Canyon: Totally shaded, this campground probably offers a better haven from the heat. The canyon’s gorgeous waterfalls will be a mere trickle in summer, but even then, the sound of running water is comforting.
• Sanborn Skyline: The few paved parking lot sites for RVs are unappealing, but the walk-in sites are excellent: shady, well-spaced and, as near as I could tell last summer, not heavily used (not for the weak of leg, though: the campground is perched on a steep hillside — schlepping gear up to it won’t be a vacation, but it might tire out the rugrats). Sanborn Skyline also has excellent single-track trails up into the Santa Cruz Mountains.

I had a much more extensive list working but a software glitch killed the rest — please fill in with your faves from around the area, if you’ve got a minute.