Dinner on the coast near Mendocino
Try "The Tides" in Bodega Bay... http://www.sfchamber.dpway.com/promotions/tides_wharf_restaurant.aspx
Saw the "Birds" filmed there and when I grew up in Healdsburg, I would eat there 2-3 times a month.
Also check out "The Sea Ranch"
I ate up there in Feb and it is still great.
re: Frank D
Bodega Bay is ONLY on the way if you take 1 the entire way, which might not be a great idea, especially at that hour if time is an issue. You will probably want to take 101 to 128 to Boonville and cut over to Manchester from there, or even go all the way to Albion and head south on Highway One...consult mapquest, but no matter what you do you are talking some very windey mountain roads, which may not make for comfortable driving if you are new to the area, but I think the Highway One route is longer. Even if you do take One, it is probably faster to cut over to the coast at Jenner....
Personally, I'd eat somewhere early this side of Santa Rosa to avoid the Santa Rosa traffic, though no matter what you do you will probably be screwed there....or, if there is no way to leave earlier, even bring 'picnic' food and eat in the car (you certainly should not count on anything in Pt Arena being open when you get there). You will be getting to Pt Arena late and (if you don't love twisty roads) a bit 'on edge' otherwise....
I want to reiterate what susan said about HWY 1. The drive from Jenner north for about 14 miles to just before Gualala is intense, windy, twisty, with sheer drop offs on the ocean side, not a good first time drive at night and if it were a foggy night, I don't care how many times I have driven it, I would go another route.
Oh, I just saw that you want to eat dinner in Mendocino. I love the Mendocino Cafe in the town of Mendocino, but there are many great places to eat in Mendocino.