Consider cornus mas. This is a dogwood with lovely yellow buds that are the first to bloom in spring in my area. It is really an understory tree that can grow up 20 feet, but can be trimmed as a hedge or pruned for a natural look. Not invasive (stays put) and in my area, needs no spraying. I inherited three cornus mas with our house that were planted in 1939. They have been stooled back several times and massively reshaped, but just keep going and going (now almost 70 years old and totally trouble-free.

But rather than a hedge of a single plant, why not consider planting a variety of shrubs to create a tall shrub border? There are lots of viburnums that will meet your needs, giving you an almost instant screen. See Michael Dirr's new book on viburnums at your library. Some are sweet scented; some keep their (dead) leaves all winter for extra screening; some can survive in fairly dense shade, while others can take full sun. The modern varieties are trouble-free, though some of the old ones, like "Nanny" can be troubled by molds.