I'm not always a fan of walking around to look at plants. However, the new canopy walk and Emergent tower that just opened a few months ago are really cool! You get opportunities to see nature from a new vantage point.
The canopy walk is a series of suspension bridges in, well, the canopy of the tree. The Emergent tower is even better. You climbing 200 and some stairs to get on top of the trees. From the platform at the top you can see all the way to Lake Erie and for miles in every direction. A really fun place to take the kids for an afternoon.
Fun fact - if you have a membership to the Cleveland Botanical Gardens, you get into the Arboretum, canopy walk, and Emergent tower for free!