The Mandeville Canyon trail is in between Brentwood and the Pacific Palisades, and is a really perfect trail for when you want to get outside but don't want to work that hard! It's an out and back trail, so there's no loop. You drive all the way up a neighborhood street, and at the very end there's a dirt parking lot. You can also park along the street in front of houses.
The trail is wide and pretty flat, although when you're hiking out into the canyon there's a slight incline. There are a lot of mountain bikers that use the trail, so you should keep an eye out for them speeding by. There are also rattlesnakes so you should keep an eye on the side of the trail. Dogs are allowed and you'll see plenty when you go!