I had the honor, when I was in Junior High, to be a part of a group of students that "beta tested" this museum. We went down to the Mather a few times a week for a couple of weeks, and did water tests, toured the boat, and learned so much about the history of boating on the Great Lakes that I am sure my head exploded on the aft deck.
I am sure that when thinking of places to visit in Cleveland, a big shipping boat is not high on your list. With the Rock Hall across the street, why would you bother with the boat?
Simple: the boat is way more fascinating than you think, and personally, the Rock Hall is overpriced and sucks.
Since I went on the tour years ago, I do not know what the pricing is today to enter. I can tell you that the boat is usually docked on the E 9th St pier, and is so friggin' huge you can't possibly miss it. It is the long black thing that has "William G Mather" in big, white letters on the stern.
When you enter this craft, you will be immediately amazed at the amount of steel used to craft this boat. The holds are gigantic.. and to think of them being filled with coal or other commodities is daunting. Pictures of other boats, including the ill-fated Edmund Fitzgerald (which I believe was the sister ship), are in the museum, along with artifacts like a ship's bell and the ropes for mooring.
I am not a big sea buff. Not really my cup of tea, but I cannot help but get lost in the history the museum has. You will learn about the dangers of shipping on the Lakes, and about the men who sacrificed their lives for the sake of maritime commerce.
You will tour a ship and see how the men lived. The engine, for instance, is HUGE! It is fascinating to see what drives a boat that size.
If you want a unique experience that is truly historical, please visit this museum. It may not be as cool as the Science Center, but it is a one-of-a-kind experience for you or your kids. And a great was to spend time together learning about our Great Lake's past.