Whale Peak
Whale Peak north approach, via the route that Jerry Schad describes in his book "Afoot & Afield in San Diego County."
On the way down, it's easy to miss the trail junction when "rolling downhill" in the small wash, where walking is really easy. And that's of course what happened to us. :)
Also, we had to hike the 4 extra miles (round trip) because of the narrow spot on Pinyon Mountain Road that I didn't dare to drive with my 2WD car (up to that spot, high clearance and some experience driving on sandy desert dirt roads is definitely recommended).