When the weather is nice I like to do a 9-10 mile run (on weekends and other days off) which has a lot of trails in it. In the winter the trails are full of snow plus I don't like to run as hard in the cold, so here is an alternate route--all roads.
Yes, I have done a bit of cross country skiing. The problem is that I have to drive to the trail, put on my skis etc. It is fun, but ends up taking a lot longer to get a decent workout.