One of my favorite year-round evergreen screens is Arborvitae Mission Techny. In my previous home, I used them to screen my vegetable garden from the front of the house. Arborvitae is a member of the Cypress family and the leaves were once used to treat rheumatism.
Techny can grow to fifteen plus feet, (some sites say twenty-five feet but this is not typical) but can easily be kept much smaller by trimming in the fall. They have very few problems with their only enemy being spider mites in areas where there is little rain. Many arborvitaes spread apart as they become larger, Techny does not do this. There is a new one that has been recently introduced a gold variety of Techny. You will probably pay a little more for this arborvitae variety but it is worth it for longevity and minimal care.