The best site has got to be Pfeiffer Big Sur, a California State Park. The H&B site is in the redwoods. A river runs through the park, swimming is allowed.
There's coin operated showers, wifi, a camp store, and a really good restaurant right in the park. The local beaches are beautiful and there shops, hotels, and restaurants. Plan to stay more than a night!
Here's a few links to California State Parks.
Central Coast Region
http://www.parks.ca.gov/parkindex/re...asp?id=6&tab=1
Los Angeles County Region
http://www.parks.ca.gov/parkindex/re...asp?id=8&tab=1
Orange County Region
http://www.parks.ca.gov/parkindex/re...asp?id=9&tab=1
San Diego County Region
http://www.parks.ca.gov/parkindex/re...sp?id=10&tab=1
Click on a park name to get info about the park.
Look at the Park Features Icon Legend to see what the park offers.
Of course, look for the HB icon for Hike or Bike Campsites.