I had a lot of experience with national parks when I was a kid, but all my experience was through old View Master, those 3D viewers. Through them I went to Yellowstone many times. It was nice to see it in person. I felt I knew the place that i was seeing for the first time.
One things that the View Master didn’t convey was the closeness of the wildlife. The bison wandered onto the road and stopped traffic. You were not supposed to approach wildlife, but the wildlife did not follow the same rules.
We saw lots of bison, no bears or elk and a few mule deer. I understand the bears are out in June & July but retreat into the back country after that. It is probably better to avoid the bears anyway.