If you prefer your campsites to be away from the smell of car exhaust, Northern California is rife with places to backpack. My personal favorite spot is located in the Sierras just past Feeley Lake. You'll find a trail map here which shows you how to get back into the untouched forest. The hike is a bit uphill but not too terrible -- I've been packing my camp gear in along this trail since I was eleven or so, so it's not too challenging even for kids. Once you get away from the road, you'll find plenty of great spots to set up camp beside small jeweled lakes. Spend your weekend swimming in the lakes, clambering around on the huge boulders and generally exploring this beautiful area. Remember to bring a water filter with you, as the water in the lakes is great to swim in but not so hot to drink.