The Great Loop is an awesome idea. If you've never heard of it, it's a series of connected lakes, rivers and man-made canals that allow a boater to travel from the Atlantic ocean, to the Great Lakes, Down the Mississippi back out to the ocean.
It sounds cool.
The Erie Canal, The Great Lakes, The Mississippi River. Relax in the Florida Keys. See major cities (New York, Detroit, Chicago) and charming coastal towns (Beaufort, Charleston, Leland).