In honor of Lathum's "Coolest city visited" thread, let me expand that to places that are not cities. It could be national parks, small towns, a region, a coastal spot, vacation spot, etc.

Here's mine (which are definitely better to visit than cities, imo):

Ouray, Colorado (of course)
Aspen, Colorado
Carmel-by-the-Sea, California
White Mountains region in New Hampshire
Finger Lakes region in New York
Eastern Shore, Maryland
Antietam Battlefield, Maryland
Cardiff, California
Sante Fe, New Mexico
Lahaina, Hawai'i

I'm not well traveled so there aren't many to choose from. Gettysburg stands out, though. I've been there a few times.

Rota, in the Northern Mariana Islands

When I graduated college, I did a cross country trip visiting many National Parks.

Some of my favorite small parks:

Bryce Canyon
Crater Lake

Todd

Pont du Gard, France (site of the famous Roman aquaduct)

Le Cliff Restaurant, Puerto Vallarta (An open air restaurant on a cliff overlookooking the ocean. Absolutely beautiful...)

fenway park

Dartmoor National Park, England. I love the little villages and ruins scattered throughout the park - very different from an American national park.

Other places I think are very cool:

Galway and Connemara, Ireland
Ashland, Oregon
Rocky Mountain National Park, Colorado
Jackson, Wyoming
Santa Fe, New Mexico

Wrigley Field
Zion Canyon
Anywhere on Guam
Nantucket Island

Big Rock Park at Blue Sky Basin at Vail, CO, after 6 inches of fresh powder has fallen.

Coming westbound out of the tunnel on Utah Highway 9 in Zion National Park.

Diving down through Glenwood Canyon in Colorado on I-70, especially when you had no clue the freeway went through it (I thought it went near it or around it).

"La Sagrada Familia" - the still unfinished cathedral in Barcelona which Gaudi envisioned and designed. When we got there, I stepped up from the subway and turned around to look for it - and got really startled as it looked as if it was right next to me!

It's huge - in fact it was about 100 yards away but it still filled my whole field of vision. When we got inside and saw all the scaffolding and construction materials, construction workers and the machines we were a little surprised. Then we used about two hours walking around the construct and tried to collect our bearings and get used to the sheer scale of it.

All in all, an awesome experience, especially when knowing how it's designed and what it's supposed to become in about 20 years, if everything goes according to plan.

the Grand Canyon
Wrigley Field
the Trevi Fountain & the Colleseum(sp?) in Rome
Capri, an island off the coast of Naples.

Yosemite, CA
Grand Canyon, AZ
Bryce Canyon, UT
Upper Peninsula of Michigan at peak color (got it just right this year)
Chicago (favorite big city)
Cape Breton, Nova Scotia
Prince Edward Island

McSweeny, you stole mine. Fenway Park. I always wanted to go and finally did a couple of summers ago. I loved the whole city of Boston. I would like to live there someday.

Kathy Bates' vagina.

Man, you could hear the sweetest echoes in there!

FYI, bring a flashlight and a snorkel.

White Mountains region in New Hampshire
Finger Lakes region in New York

thank you AnyBucc for reminding me of great times at those locations

Key West, Florida
Boundary Waters Canoe Area - Minnesota/Canada
Sleeping Bear Dunes - Michigan
Wildcat Lake - north of Boulder Junction, Wisconsin

All the Black Hills stuff in South Dakota, Met Stadium in Minnesota, lots of weird TV & movie set crap in and around LA, the Tiajuana border crossing, Pere Lachaise cemetary, the Gilman in Berkeley, 1st Avenue during the Purple Rain filming, various places the Beatles played in the USA and Europe.