Lisa is entirely correct.
I think that the plan has moved away from going to Oregon, but what I should have said is that, for the relative amount of time one is driving, I would prefer to take 101 straight up to Eureka, and then see the more-rewarding (more concentrated scenery) Southern Oregon coast. I honestly do not remember Mendocino very well--I shall have to make a point of going there this Summer when I drive back from Toronto. I seem to recall a big draw being the funky architecture, and for that, you might try Half Moon Bay or (more upscale) Carmel-by-the-Sea. Nothing to compare to the Russian Gulch area, with its blowholes, though.
There are some interesting things on the Highway 5 corridor once you get somewhere North of Redding, but even then, photographically, they are generally hard sells better left to those with local knowledge. (Shasta and Black Butte seem like they should be photogenic, but they really aren't when compared to just about any volcanic mountain in Oregon or Washington. Castle Crags really needs atmosphere and the right angle. Most of the lakes are actually reservoirs, with ugly banks. You get the idea.)
I have never seen the excursion train in Willet, but I have been on the ones in Niles Canyon (out of the way) and at Roaring Camp (lots of fun, nice looking train, but I don't recall there being any really good photographic angles). If you are really into trains, there is a good train museum in Sacramento which, despite being the capitol is otherwise almost completely uninteresting.
Lighthouses in the area tend to be on cliffs or hills above the sea, rather than dramatic rocky points with nice angles (don't think we don't lament this). Point Bonita (Marin headlands) is worth dropping by if you are there, but hard to get an angle on when you are close and closed at sunrise/set. Pigeon Point is midway between Half Moon Bay and Santa Cruz; it is very tall and probably needs a really good sky to make the photo. Point Santa Cruz/Lighthouse Field State Beach is somewhat homely as a lightstation, but right in Santa Cruz--you could photograph surfers in the late afternoon and the boardwalk toward evening. I attended UC Santa Cruz yet never went to the Marina light, but it is right in the city too. Point Piņos, near Monterey, is a nice lighthouse, but far from the shore and lacking in particularly good angles for photography, mainly due to two large trees on either side of it. Alcatraz also has a lighthouse, which is mainly interesting if you are shooting that way at night, dusk, or dawn.
If you are interested in seeing the elephant seals at Aņo Nuevo (the lighthouse is gone), they will no longer be breeding, but it may be worth calling and asking the park rangers about the conditions at the beach when you will be there. Might be a good mid-day activity if you are on that section of coast, to see Pigeon Point, or just driving by.