The view of the Grand Canyon at sunrise from Bright Angel Point on the North Rim is overpowering. You walk out along a narrow ridge line and stand at the point (with guard rails) and the canyon is all around you, almost 360 deg. around and a mile down.
Also, the view of the Grand Canyon from the back of a mule.
Sedona, Az red rocks, especially the rock art at the Palatki Ruins
Acadia National Park (Bar Harbor), Me.
Denali National Park - Seeing the "Big 5" on one trip. Wolf, Grizzly Bear, Moose, Mountain Sheep, and Caribou. Alaskan moose make New England moose look like wimps.
Brooks Camp at Katmai National Park; Bears, bears and more bears feeding at the salmon stream. Getting stuck in "bear jam" when the dinner bell rings and having to wait for a hour or two until the bears decide to let you go.
I also forgot; the village of Telluride, CO., truly stunning in its setting tucked into a box canyon in the San Juan Mountains. Drive Rt. 550 from Ouray to Silverton, possibly the most beautiful paved road in the US. Then rent a jeep (or take a tour) and drive some of the old mining roads.