Snowboarders have gravitated toward using them on places like Teton Pass as a means of accessing backcountry ski terrain. The heavier-duty models are quite efficient for side hilling and climbing steeply. And in the spring snowshoes really come into their own. They can be an efficient way to travel over a hollow snowpack when even skis will break through. Their wider surface area allows them to distribute weight over a large area.
Snowshoes come in a variety of shapes and sizes.
Generally, most companies produce a recreational model for use on flatter and rolling terrain, and a beefier line for people who will be venturing into the mountains. Many lines are available in three sizes, which roughly equate to peoples' weight. Smaller folks will buy the smaller models and larger ones use the bigger snowshoes. Some people, however, will buy a smaller snowshoe if they will be running or using them only on consolidated spring snow. And similarly people might buy a larger model if they will only be snowshoeing in powder snow or frequently carrying a heavy pack.