I would look into Hemlock(Tsuga). In the last week or two Home Depot has been selling them in three to five gallon sizes for use as Christmas trees. I have wanted one for my garden for a long time, but all I ever found were huge balled and burlapped plants that I couldn't move, much less put in the ground! I may take advantage of the seasonal offering from HD myself. I am so sorry you will be losing your privacy, I know how important it is. There are subdivisions popping up everywhere lately!

The parsonage for my church had the exact same thing happen about 5 years ago. For many years there was nothing but woods as far as you could see behind the house, it was fabulous. Now, John Wieland has put in a huge subdivision and there are houses all around the back of the parsonage. I never realized before the subdivision went in, just how small the parsonage lot is. There is a storage shed about a hundred feet or so in back of the house. Wieland put up a 8 foot solid wooden fence around the entire subdivision and the part that borders our parsonage is within a foot of the storage shed! It does little to hide the new homes from view.

You might also want to consider planting other evergreens too. Osmanthus, Little Gem Magnolia, Chindo Viburnum, maybe even some Southern Indian azaleas(tall evergreen)I'd get started on a buffer as soon as possible! Good luck.

Bamboo grows like nuts even in shade... just make sure that you contain the roots as it's an invasive species. My Aunt has it growing under her redwoods [very shady in acidic soil] except poor thing she doesn't want it and can't get rid of it. A brick or cement planter along the back of the property would do the job to help contain it... it could be 10-15ft or higher in one season.

I recommend american holly. It doesn't grow tremendously fast, but it makes a great screen eventually. You may want to place them between other, faster-growing trees. I also like the canadian hemlocks.