It depends on what time of year you are planning on coming here and what your interests are. Eureka, and Humboldt County in General, are best known for our numerous parks and wildlife. These include both state and national parks. Eureka also has a zoo, which is a big deal for such a little town. Admission is $4 for adults. We have vast stretches of beach that are open to the public within a few minutes drive, including Patrick’s Point State Park, the Clam Beach Recreational Area (4×4 driving is allowed on beach there) and Cape Mendocino to the South. Old Town in Eureka is also a favorite tourist attraction. We definitely don’t have any “Disneyland type” attractions, but this ain’t Anaheim. 🙂 A couple of websites that you may want to check out for more info are below:

http://humboldtonline.com
http://humboldt.craigslist.com
http://times-standard.com
http://www.humguide.com

P.S. I’d recommend The Red Lion Inn or the Bayshore Inn. They are moderately priced and service is good. If you want the best possible “Eureka Experience”, I would highly recommend The Hotel Carter. It’s in a class all by itself. There are also a number of great bed & breakfast inns in Trinidad, CA, just to the North of Eureka.