For those of you who are unfamiliar with the Sacramento/Norcal area, Folsom Lake is the 9th biggest lake in California and is really beautiful.
You can enjoy the best of camping, with miles of hiking/biking trails, boating and loads of beach surrounded by calm, predator free water.
You can visit Tahoe, Napa, Sonoma, Amador County (amazing wine), the redwood forest, the Sierra Nevada foothills, Mendocino/Fort Bragg and Yosemite all in less than 3 hours.
Most of these are only 1.5-2.5 hours away, but Yosemite is closer to 3 hours.