First, most stunning depends upon the criteria. I know some photographers who argue that the mix of people and styles in New York City is "stunning" b/c they live for street photography. I know other people who would go "urban life stunning? Pfft!" One person's "stunning" is another person's "how boring" in many cases.
Second, a lot depends upon the time of year or setting. Lots of ash and sediment in the air and you can get amazing sunsets. I've been in Florida at Ft. DeSoto and shot some sunrises where it's "ok, there is a sun coming up today" and some at the exact same location where it's "holy f*ck this is so beautiful!" Logan Canyon in Fall with the Aspens is a different experience then Logan Canyon in August when stuff is kind of brown.
Third, this is from a photographic bucket list that I keep of places I want to shoot (or have shot and want to go back again):
Peek-a-boo Gulch in Escalante Utah, Iguazu Falls in Brasil-argentina, Channel Islands National Park in California, Meridian Hill Park in DC, The Wave in Arizona, Cinque Terra in Italy, Eze in France, the Namib Desert in Namibia, Yosemite in Winter (CA), White Sands in New Mexico, Waterholes Canyon in Arizona, Colorado National Monument (similar to The Wave), Pastel Canyon in Valley of Fire Nevada, Zebra Canyon in Utah, Happy Canyon in Utah, multiple locations in Valencia Spain (Palau de les Arts Reina Sofia, City of Arts and Sciences), Kreeger Museum in DC, Mitchel Rales collection--the Glenstone Museum--in DC, Flag Ponds Park in Lusby MD, Cunningham Falls State Park in MD, Hunting Island State Park in SC, Washington Oaks Garden State Park in FL, Fernandina Beach in FL, the whole freaking Oregon Coast (Derrel is spot-on: the most diverse coastline in the world for a 100 mile stretch), Tallulah Gorge State Park in GA, Cumberland Island National Seashore (GA), Caladesi Island State Park in FL, Edisto Beach in SC, Folly Beach in SC, the falls in Sleeping Giant State Park in Hamden CT, Indiana Dunes in Indiana on Lake Michigan, Gare de Liege-Guillemins in Liege Belgium, Red River Gorge in Kentucky, the Apostle Islands in Wisconsin, Makoshika State Park in Montana, Brunei Dunes State Park in Idaho, Chengyang Bridge in Sanjiang China, Millau Viaduct Bridge in France, Puente de Alamillo in Sevilla Spain, Bushwick Inlet Park inBrooklyn, the John and Frances Angelos Law Center at the Univ. of Baltimore in MD, the Sustainability Treehouse in Glen Jean WV, the Amazon, the Stari Most Bridge in Mostar Bosnia, the Vasco de Gama Bridge in Lisbon Portugal, the inside of the Broad Art Museum in LA, the CIT building at Dulles Airport in VA, the Rainbow Canyon at Lake Powell Utah, the San Rafael Swell in Utah, Rattlesnake Canyon Page Arizona, Secret Canyon also in Page, Bannerman Castle on the Hudson River in NY, Salar de Uyuni (the salt flats) in Bolivia, Hotel Monaco in DC, the staircase in the Old Executive Office Building in DC, Buckskin Gulch in Utah, Antelope Creek Canyon in Page Arizona (upper and lower), the George Peabody Library in Baltimore MD. Yellowstone is a bunch of places. I've shot the Getty Museum probably 4 times and could go back again and again. Yosemite (but this time in the winter with ice turning to flame when the sun sets). And then instead of a list of places there let me just say: Iceland--all of it. In summer and in winter, on the coast and inland.