A mix of tall trees and lower-growing shrubs is best in a border area. If you don't want flowers or fruit, evergreen trees would narrow your choices but still provide you with privacy. Try Arizona cypress (Cupressus arizonica), Eastern red cedar (Juniperus virginiana) or pines (Pinus spp.). As to the shrubs, some medium-sized ones to plant in front of the trees are Glossy abelia (Abelia x grandiflora), Mahonia aquefolium (Oregon holly) and Fragrant sumac (Rhus aromatica).