I'm a little bit late in this discussion, but have (at least) one more thing to add.
I've seen a few places both in the US, Canada and Mexico, but two still stand out to this day.
The first is Bonaventure Island in the Gaspe, Quebec, Canada. Out of the way, but a great trip to the island when the birds were breeding. Thousands of gannets and no room to walk.
The second is in the Southwest. Cedar Mesa in Southwestern Utah. Many spots to go to, like Butler Wash or Arch Canyon. The best probably being the Grand Gulch. Lots of Indian (or Puebloan or Native American) ruins with pictographs en petroglyphs on the canyon walls, lots of one or two story remains of the buildings these people lived in, some of which are still in a remarkably good condition. Some areas are difficult to reach, other are along the roadside.
Van Williams