Welcome, Ned!

I'm going to have to play 20 questions before making suggestions so bear with me. Your elevation will narrow down the choices. I think you're too high up for the Green Giants, but I might be wrong. Have you seen any in your neighborhood?

What kind of soil do you have? Sandy or clay? What height and spread are the max you could go? Are there power lines, light poles, etc in the area? How wide and deep is the planting area? What kind of colors, textures and shapes appeal to you? I'm thinking you want evergreen for privacy, not something that'll lose it's leaves and be open in winter.
Is it in a lawn area that will get water?

Fast growing usually equals weak wooded, so you may want to consider a double staggered row, putting the slower growing but longer lasting plants to the streetside and the faster growing on the house side. That way you get the coverage you want and you can remove the weaker plants if necessary when the streetside plants get some growth on them.

I will suggest you go with smaller plants to start. That's been the hardest lesson for me to learn. I know you want instant gratification but smaller plantings go through much less shock and will ultimately outgrow the bigger plants.

This link may help:
http://www.ext.colostate.edu/pubs/garden/07403.html

It's not specific to high altitude, but has links for high altitude plants. I thought it would be a good place for you to start.

It'll be a fun project and I think your planting season is getting near.

Come back and let us know what you're planning!

Barb

Those 'green giant' trees won't do well at all here - I planted 50-odd, 8 years later have about 6 left, and the tallest one is maybe 6 foot high. It's just too dry.

The fastest thing you can do is a fence with vines.

Second fastest would be a hedge with honey suckle bushes, but you'll get tired of those in a hurry.

Then there are lilacs - take a bit longer, but are easier to deal with in the long run.

Juniper scopulorum hybrids would work as an evergreen if you can supply additional irrigation in the first season or two during dry spells. Interplanting in a staggered effect with Yellow Clove Currant (Ribes odoratum), Ninebark (Physocarpus), Lewis Mockorange would lend additional interest and color. Going more native or at least drought tolerant would be a good idea. Visit a Summit county nursery for local advice aon what will and won't grow in your specific location.