I came here on a gorgeous late autumn day with still-yellow and red leaves in crunchy piles on the green grass, so is a huge factor in my opinion of the grounds. (It's beautiful!)
I had only an hour so I went to the Garfield Monument and the Wade Chapel, taking the route that passes by the Rockefeller graves. I'm not from Cleveland, so for me (besides the Rocks) there were just a lot of names. I thought it especially poignant the gravestones for Baby ("BABY") Briggs and who, if you do the math, were young children, and the birth & burial of whole generations; as well, the carved story of a family's journey from Europe due to religious persecution (they were Huguenots) passing through Brooklyn (where I live) to Cleveland and the Midwest.
I'd like to give a shout-out to the female docent at Wade Chapel. It's a gorgeous structure, but having someone explain it and share it with you makes the experience so much more. I probably spent about half an hour in there, discussing with her the mosaics and the floor and the doors. Have the guide take their big flashlight and shine it over the details on the walls, and especially those rosettes on the pews. Surprise!