Dutchman Flat is a 6.5 mile trail located near Sunriver, OR. The trail is good for all skill levels and primarily used for cross country skiing.
cross country skiing
I highly suggest you do this in the wintertime after a nice snow storm. The views are absolutely amazing. You are cradled in a valley surrounded by 6 mountains... Mt. Bachelor, Tumalo Mountain, the 3 Sisters and Broken Top. There are trails somewhat maintained even in the winter snow, but I highly recommend snowshoeing.