Yellowstone: what's the big deal about it?

Been there a dozen times since '86. Stayed both in and out of the park. Short trips of a few days to ten days. We are there end May- June or Labor Day - October. We've traveled alot around this country of ours and have yet to find a place that has such a variety of things to see and do. Getting up before sunrise to see wolves and bears and moose.One of the best trips we had was the year we saw a Grizzly and four cubs, very rare. Went back every day to watch them feed and play. We returned the following year and she was still in the same area but only had three cubs. Sad but it's life.Hiking,geysers,paint pots. Just eating lunch by the rapids. It's not an amusement park so there's no instant gratification, just see it at a slow pace and enjoy it.