With over 150 ice routes in less than 3 square miles, Hyalite Canyon represents the most concentrated, natural ice climbing venue in North America.
Home to all-time classics like "Cleopatra's Needle," "Black Magic," "Mummy Cooler," "Winter Dance," one of the top ten routes in the world (yes I said world), Hyalite is unique in every sense of that word.
The South Fork (Cody) might have more vertical but it's spread out and inconsistent with scrappy approaches. Keystone Canyon and Lake Willoughby certainly vie for the densest cliffs on the continent except for perhaps a few fjords in Newfoundland and Quebec once every 10 years. Ouray has way more concentrated ice than anywhere but most of it is in the ice park; the climbing equivalent of farm raised salmon (and about as overcrowded). Of course the Canadian Rockies, both the Mecca and Medina of the frozen world, has over 10 times the number of routes and all of them longer – but over an area roughly the size of Maryland. North Conway has killer ice; when it's not raining. I've been to them all so cut it anyway you like, declare yourself a hero because you prefer long alpine or mixed climbs, stir in whatever hyperbole you favor and pass the single malt; Hyalite is the most concentrated, easily accessible and consistent ice climbing venue in North America. And I'm not the only widely-traveled climber to say it's our favorite too.
South of Bozeman, MT about 45 minutes from Downtown, depending on road conditions. Routes range from 10 minutes to 2 hours from the car. "Winter Dance" is the definitive guidebook in full color. www.firstascentpress.com/winter-dance.html
If you only have a few days to climb, make sure you go to the unamed wall. Its by far the best way to get a lot of climbing in. The rest of the climbs are spread out all over the place. On second thought, go to Cody.