The Doumont area is actually a large collection of trails that begin at the end of Doumont Road. From here you can hook into other trails and logging roads that end up on Mount Benson to the south or Lantzville foothills to the north. They can be a bit confusing so I recommend riding or running with someone who knows the trails well for the first time or take a map with you. Phil makes an amazing Doumont map and keeps it updated. You can get one of those here http://www.island.net/~pmcgarri/
Roberts Roost is a great little trail up to the east ridge of Mount Benson in Nanaimo. The trail meanders through Morrell Sanctuary, across the powerlines and hang a left at the first major intersection and across the logging road. Head up the hill from here up onto the ridge.
The trail around Westwood Lake in Nanaimo is a beautiful barkmulch and gravel trail that goes around 5.5 to 6 km around the lake. There are kilometre markers along the way so you can see your progress. The 2 large parking lots are right on the water and provide a great base to go swimming for a few hours. Washrooms are between the 2 parking lots and are open most days.