Updated 2011 - M. D. Vaden
The photo shown below is one of my favorite evergreen conifer ornamental plants, called Blue Giant Sequoia. Sequoiadendron giganteum 'Glauca' or 'Glaucum. It is native to the western United States in the Sierra Nevada mountains. The blue variety seems to grow a bit narrower than the straight species. These trees grow enormous, but keep in mind that if you center one of these in the yard as a specimen, you can enjoy it for at least one lifetime, and maybe the next generation following. I have considered this Giant Sequoia for our own front yard, in the middle of a 25' x 25' space, with the intent that we can get at least 40 to 60 years of enjoyment. Even the green straight species are exceptional specimens.
For details, read the Wikipedia Sequoiadendron page. Don't let the dimensions there intimidate you. This genus has its place in certain urban locations, and can last for centuries.