Don't forget waterproof / water resistant / water repellant shoes, if wet weather is a concern. Wool socks, in theory, keep you "warm even when wet," but I learned by sad experience on a golf trip that the socks were not enough to do the job with shoes that were not water resistant, etc.
That having been said, I've been happy with Smartwool for years - they make a wide variety of socks in thickness and styles. Choose carefully. However, based on A.G.'s advice I'm going to check out the Kirklands at Costco.
Edit: P.S. - my Costco did not have the men's in stock. They did have the women's Kirkland "Trail Socks" which appeared to like Smartwool -- 3-pair package for $9.99.