Southeast of Zurich, St. Moritz (pop. 5100) is a real paradise for serious cross country skiers. There are over 75 miles of maintained tracks around the town plus another 200 miles along the valley.
To reach this area from Zurich, head southeast on Route A3 and then south on Route A13 to Chur. Turn south on road to St. Moritz for 70km.
Overall, St. Moritz is the 1st most popular cross country ski area of all 22 Nordic ski destinations in Switzerland.