Here's a link to a comparative chart for grasses which will be hardy in your zone. Heights and hardiness zones are included for each grass.

http://www.bluestem.ca/grass-comparison-chart.htm

Something to keep in mind, when considering grasses for screening...they will only provide privacy for about 2/3 of the year. They need to be cut down to the ground in late winter, and will take at least 4 months to grow back to full mature height.