I completely agree with Matias on this, Arcata is what you want. There is an old hotel right on the town square, it's a bit funky but a cool place to stay. Great little cafe on the square, great food and coffee in general in that whole area, so many nice markets. Eureka has some cool historic neighborhoods to see as well but is generally more sketch. I definitely wouldn't stay in Crescent City myself. But some people have recommended the casino hotel up there. I really love Trinidad as well but not much to walk around to, better lodgings though. For trees Prairie Creek is my favorite but Avenue of the Giants is also so so nice. Check out Bull Creek and Rockefeller Grove for sure. Definitely worth a drive out to Ferndale as well, lots of nice Victorians there. Hope you have a great trip, one of the nicest parts of the country imo.