If you want to take a quick hike through the Santa Monica mountains, then there is nothing better then Temescal Canyon. Simply drive north on the PCH (1) toward Malibu and turn onto Temescal Canyon Rd. At the end of the road will be the entrance to the hiking area. NOTE: You can park for free on Temescal Rd, but have to pay if you go inside the actual park. Save the money...the entrance to the hiking trails is only a couple of hundred yards from the road.
Once at the top you will find a view all the ocean communities and downtown Los Angeles. This is a light hike with a few uphills. Just make certain that you bring water, as it can get a bit hot when not in the shade.