Try "Afoot and Afield" hiking guides for San Diego, OC, LA or Inland Empire. Great detailed info for long and short hikes of all degrees of difficulty. For many years, the author was Jerry Schad, but Scott Turner has been taking over. Remember, all who wander are not lost!
"Mount Baldy from Manker Flats. 3800 foot elevation (to 10,000 feet) in about 4 miles. But would wait for spring, too dangerous in winter.
My favorite hike has always been the trail from Mount Baldy to Lytle Creek. It's a 10+ miles hike but I haven't been up there several years. Maybe the forest service cut off access to some of the trail due to motorbikes compromising sensitive habitats. Not sure but a determined adventurer can probably work around that.
If ya looking for a good side trip, find the trail to the top of Cucamonga Peak. Its that flat top mountain east of Mount Baldy.
On a clear windy day, ya'll can see Catlina Island and the entire valley from Santa Monica to guessing San Clemente from that Cucamonga Peak.
Buck Gully is a nice short hike right in the middle of Newport in the hills above Corona Del Mar.
5.25 mile loop with fantastic views of Catalina and Newport Harbor from the top. If you’re near there and want to get in a couple of hours it’s a great choice.
Humber Park to San Jacinto peak will kick your ass (not in winter)
Ladder/Painted Canyon in the Mecca wilderness (not in summer)
My place to the liquor store (anytime)
. Laguna Coast Wilderness.