The Lake Wenatchee State Park Sno-Park groomed trail system is divided into two areas by the Wenatchee River that feeds into Lake Wenatchee, separated north and south. The south trail system has more loops and shortcuts than the north, and tends to be more crowded. The north trail system is primarily a single longer loop that goes through forest and then along Lake Wenatchee and the Wenatchee River, with a few short inside loops through a summer campground. The north trails are mostly gradual and level, with an occasional short steep section interspersed. The north loop is especially pretty since it opens up to more views over the water and out to the surrounding mountains.
Links:
Lake Wenatchee State Park
Trail map
Sno-Park permit
Reference:
Cross-Country Skiing: Building Skills for Fun and Fitness
Basic Illustrated Cross-Country Skiing