One thing everybody enjoys about the Rockies is sighting the very occasional bear, and grizzlies are the truly rare ones, the bears you want to see. This Associated Press article with accompanying cute photo from the SFGate website might leave you with the notion that everybody who comes here sees bears.
The opposite is true; in recent years most tourists in our mountains never see a bear. The National Park Service has done a relatively good job of driving bears away from people-frequented parts of the parks. They've closed some campgrounds, made other areas off-limits to hikers, and tightly control the garbage which once was a bear magnet.
Fifty or sixty years ago everybody saw bears, they hung around people and begged for food. As a kid I took a photo of a bear with its front paws on the windowsill of an auto. Unfortunately, bears also injured or killed people.
----------0----------
Living nearby, the DrsC visit the parks often, on our own and serving as tour guides for out-of-town friends. Most trips we don't see a bear. When we do we assure our guests we've been very fortunate.
Local lore says there are the "big five" that tourists in the Yellowstone/Grand Tetons park complex want to see: elk, moose, bison, bear, and wolf. Actually there are more than five, you might also see big horn sheep, pronghorn "antelope," deer, marmot, beaver, and coyote.
Bison are easy to see, they are North America's wild cattle and in Yellowstone's Hayden Valley they behave much like cattle. Deer and elk are relatively common, and coyote are often mistaken for wolves.
Moose, bear, and wolf are harder to see, and require some luck. Beaver are common but do most of their foraging and construction at night so aren't often seen, although their dams and lodges are easy to find.
Pronghorn are very common on the prairies of central Wyoming but are not common in the national parks. They are attractive animals, although local hunters call them "goats."