If everybody could post their area's State Park websites, we would have a wealth of information! Here are the one's in my area:
http://www.state.tn.us/environment/parks/
http://www.arkansasstateparks.com/
http://www.mostateparks.com/ (Missouri)
http://www.dcr.virginia.gov/state_parks/index.shtml
http://mississippistateparks.reserveamerica.com/
http://www.alapark.com/ (Alabama)
http://www.floridastateparks.org/
We usually stay a State Park campgrounds, especially in Tennessee - we have the best and I think the most. We also love National Parks. You get the best surroundings in NPs, but at the expense of any hook ups. The US National Parks website is:
http://www.nps.gov/
Enjoy!