Two good long ones to start with on the west side: The stairway down from the lower parking lot overlook that I call the "Merrie Way" has about 127 steps (pics 1, 2).
From the top of this, around on the curvy walkway and up the 57 steps (ninth pic) to the upper parking lot overlook, the El Camino del Mar trailhead to the east.
Up through the forest from here to the old Fort Miley ruins: 22 steps up the first flight (this one visible to anyone in the area: 10th pic), where I hang a left for the zigzag/sand part of "Tony's Trail" (pic 11). Tony's Trail never disappoints, but there are other short, secluded trails off the main ones.
Another I like is a short N-S between the El Camino del Mar and Coastal/Lands End Trail. Could've easily continued down to the Coastal Trail if I'd wanted to. There's excellent shelter for birds and other critters, perfectly walkable for those who seek out wilder, offshoot trails (pics 12, 13).
The longest stairway in the park is down to Mile Rock Beach from the main Lands End Trail, with 272 or so steps (14th pic).
A little further along the main trail is the "Painted Rock" stairway (15th pic), about 138 to the top, then about 117 down the east side.
Before doing much of the east side, however, detoured up a short but steep trail that comes out at the golf course. Took the paved walkway here out to the end of the Legion of Honor Museum's parking lot and down the 47 steps to the El Camino del Mar, the less traveled, upper, main trail, across the wood footbridge and down the connector stairs (last two pics: 89 steps) back to the main Coastal/Lands End Trail.