It depends on how much room you have, spruce spread too much arborviatae don't but then you have the snow problem. Personally I prefer hemlock because they can be sheared once a year and still look natural.

Here is a link that might be useful: Propagating Perennials

Serbian spruce and oriental spruce stay more narrow and are very attractive. If you want to get creative you could plant a combination Oriental, serbian and blue spruce and add in the cultivars 'Hoopsii which is very blue and 'Skylands' which is very yellow. Add in a couple of pines and a few Green Giants and it will look great.

If money isn't an issue you can even consider american holly. It is very pricey for larger plants but very attractive and the female plants have red berries in winter.
David

Just a word about the Hemlock....they are really taking a hit in the NE with a pesky insect called the wooly adelgid. My brother (also in a suburb outside of NYC) had to remove some real beauties a couple of years ago.

And you want to look CAREFULLY at the real mature heights and widths of any tree you are contemplating - do NOT go by the hang tags on them in the nursery, as that is frequently the expected height in 10 years - they keep on growing after then!

If you don't want tall trees, then evergreen shrubs should do. You CAN post on the shrub forum if that's the case, but most of the same people are in both the trees and the shrubs, so you probably won't get any different advice. Shrubs CAN grow up to 15' tall before they slip into the tree category (and some classified as trees can stay smaller than that - Japanese maples for example), but I don't know how tall you are looking for.

As well, you will get better advice if you can say how much sun/shade the area gets.

Agreed dibbit. I've seen some ridiculous examples of conifer "screens" planted way to close to property lines or houses. In my town, there are 2 houses that are only 30 feet apart AT MOST and there is a hideous row of Leylandii between them.

In most climates there really is not a perfect screening plant. The ones that grow fast generally grow too big. It's all a trade off, my advice is plant something slower growing and be patient but people aren't patient these days. I have seen in old gardens in the mid-Atlantic, from DC up to the Philly suburbs, that there are old arborvitae hedges that seem to have "matured" at a reasonable height. The plain old Thuja occidentalis. I think the hybrid 'Green Giant' will, with time, become a giant, given it's parentage.

Plant two staggered rows of more slender growing trees which are known to reach the heights you desire.

Do either you or your neighbor have a two story house? If so the tall Thuja 'Green Giant trees' potential 50 feet height potential and 6-12 feet spread does not seem too tall. The Thuja Standishi grows slightly more short if you do not want to plant any trees that could grow 50 feet tall in that area.

In a posted reply above, picea seemed to have good suggestions on a variety of trees, which could be used to create a more interesting privacy planting.