Museums.
I know the art museum is a must see thing. Is the natural history museum in that area really cool? It's not free like the art museum. There is also a botanical garden in that area. The video of Great Lakes Science Center make it look like COSI in C'bus... like it's more for kids than adults.
Other places we will probably go (besides the obvious Rock Hall visit):
Cool downtown places (4th street comedy club, Playhouse area, etc)
Little Italy (+ maybe the Conventry shops incl. City Buddha, the Peru thing, the Candle making place which is not a huge big deal because I made my own double-boiler to pour my own candles here at the house when I get motivated to) but if their candles are as good as the ones from Amish country in Ohio, then I might buy some.
Westside Market and nearby brew houses.
That monument in the middle of downtown to the WINNING side of the civil war since I get tired of seeing all the tribute crappola to the butt-hurt loser side in the area where I live.
As far as visiting the quint little towns like Chagrin Falls, that might have to wait for another Cleveland trip.
You've got a pretty solid itinerary there. A few notes to consider. Covid has really gutted the West Side Market, making it a bit of a sad shell of its former self. Even before Covid, it was struggling as fewer people were shopping there and more were treating it as a tourist destination and the city mismanaged it to hell. Some of the best vendors are gone, and there's a lot of vacancy. Still a lovely space and well worth the trip, but not what it once was.
And there are no less than seven breweries within a mile, including Great Lakes (know commodity), Hansa (decent and with a great European market attached), Nano (same owner as Market Garden), Market Garden (solid lineup), Bookhouse (great space, hit-and-miss beer), Forest City (great space, crap beer), Brick and Barrel (cool spot near the river but for hopheads only). If you're really into beer, I recommend Noble Beast on Lakeside and Masthead, which is nearby and also downtown. Two underappreciated good spots.
Speaking of downtown, it's been crushed by Covid. Michael Symon's Lola is closed permanently among other fixtures on E. 4th. Downtown in general is pretty dead, as it relies heavily on events and office workers. So calibrate your expectations accordingly.