Cedar Point is fantastic.
Six flags Great America is also very good.
http://www.sixflags.com/greatAmerica/index.aspx
My favorite amusement park is Cedar Point in Ohio, with plans to go in late August before the season ends to beat the crowds.
Also, The Great America in Gurnee, IL removed the Iron Wolf rollercoaster, which was a favorite of mine. Bummer. :crying: