I almost always see mule deer when doing a trail run that passes through Trippet Ranch, especially in the morning. They tend to hang out near the parking lot, the pond, the oaks along East Topanga fire road, and along the Musch and Dead Horse trails.
Sunday several doe were grazing about five feet from the parking lot, and barely took notice as I (slowly) ran past. I also saw a buck near the start of the Musch Trail, but he was much more skittish, and strutted into the brush as I ran up the hill from the pond.
Related post: Musch Trail Mule Deer