-Pennsylvania- Gettysburg, Valley Forge
-New York- Niagara falls
-Washington, DC: Washington monument and other monuments that I can't remember right now.
-Georgia: Stone Mountain (is that a national park?)
-Washington state: Mt. Rainier, Mt Baker
-Oregon: Cannon Beach (?), Mt Hood, Craterlake
-Montana: Glacier National Park
-California-Alcatraz Island, Death Valley, Golden Gate, Muir woods, Point Reyes, Yosemite.
-Arizona- Grand Canyon
-Hawaii- at least two volcanoes. I don't know the names.

We didn't start going to national parks until we moved out west. Now we are trying to see as many as we can.

You can find national parks in your area here. http://www.nps.gov/findapark/index.htm#