San Clemente State Beach gives you a fun change of pace after being in the California desert. The beach and greenery will liven your photos.
You’ll be treated to a day-long parade of Amtrak Surfliner and Metrolink trains and decent sightlines will let you know when they are coming. Do note that the pedestrian crossing is at grade so you’ll be stuck on one side of the train until it passes.
Winter provides the best range of photos. You will be able to shoot southbounds just about all day, just start on the east (parking lot side) in the morning and move to the ocean city in the afternoon. In the summertime, during the weeks leading up to and right after the summer solstice, it is also possible to shoot northbounds for a few hours in the late PM from the ocean side of the tracks.
Be sure to follow all applicable signage regarding beach use and parking.