Simi Valley is really a valley, sorrounded by mountains on all 4 sides, which give excellent options for hiking of all sorts.
You can hike daily on Mt McCoy, or go on Rocky Peak or Simi Peak. I have few times started from Long Canyon trail head, climbed Simi Peak, then have got down at the Oak Park side and then came back on Simi Peak and then back to Long Canyon Trailhead- total 16 miles with around 3000 feet elevation.
Here is the route- Simi Valley to Oak Park via Simi Peak.
Enjoy Simi Valley highlights. Here is a slide show of photos of Simi Valley that I have taken over years. I prepared this presentation when I was invited to speak at a brown bag session at Royal High School, Simi Valley. You can click on the three buttons and choose to watch this in full screen.
Simi Trailblazers seems to be a group that gives us many in-the-area as well as out-of-the-area hiking alternatives for Simi Valley residents. Here is the link to best simi valley hikes on Trailblazers website.