[font color=\'#000000\']If you haven't seen old-growth redwood forests yet (and they can be stunning!), there are several great redwoods parks within an hour or two of SJ. Big Basin Redwoods State Park is the best of them, but also one of the farthest (check mapquest). Portola State Redwoods Park is a closer good one (fewer of the really huge trees, but still well worth it).
If you have a whole day and like photographing seashore areas, the Monterey peninsula is a great day trip too (sea lions and sea birds, historic buildings in Monterey, rocky seashores in Pacific Grove, the famous 17-mile Drive, etc.).
There's really nowhere I know of that you're both allowed to go and that requires 4WD anywhere near SJ, so no need to even think about it.
Of course, if you have a whole weekend, it's less than four hours to Yosemite Valley...