I rather agree with bid_time; the lakes themselves are, well, great big lakes, large expanses of water.
There are plenty of fine things to see in the region. Niagara Falls is an obvious example, if somewhat commercialized. There are quit a few cities with fine museums and cultural institutions, many lovely state parks, some pretty roadways along the shoreline, some amusement parks....
I think it would be fun to take the SS Badger across Lake Michigan (and doubly so to avoid driving around Chicago). It's not especially inexpensive, though.