After our first go at snowmachining, I can absolutely understand the attraction of the sport. We spent a good afternoon traversing a 40 mile loop through incredibly scenic landscapes in the Petersville area, south of Denali. This was the perfect location, with vast areas of open space providing plenty of opportunities to pick up decent speed, and our Ski-Doos had no trouble at all getting up to speeds of 90mph before common sense reigned them in. Something we would definitely try again, though probably not this season given the rapidly melting snow.
The Petersville trails are a 2.5 to 3 hour drive from Anchorage. Take the Parks Highway north, past the Talkeetna and Trapper Creek turn-offs. Gate Creek Cabins have snowmachines for rental and the trails are easily accessible from the cabins.