Any of the ornamental grasses would look nice, but you have to chop them down in the spring, so there are a couple of months while they are growing back where you wouldn't have much privacy.

For year round use, I suggest evergreens. Junipers are really tough and come in various heights and widths, perhaps yews. Do you know your gardening zone?

They wouldn't provide any privacy in winter, but I've had good luck with Cattails. I have both mini and regular cattails.

They don't take any maintainence, just keep the water topped off, and they winter fantastically. I've got several shoots coming up already!

This picture shows the pond area around May 20, you can see the cattails coming up in the back.

Here is a link that might be useful: {{gwi:1237}}

Another possibility would be to try bamboo if you can find a hardy type. Scanning around, there is one called "Grove bamboo" (Phyllostachys aureosulcata) that is supposedly hardy to at least Zone 4. Note that when you plant in containers, you want to aim for plants hardy 1 - 2 zones lower than your actual zone (unless you have a way to protect the container/plants in winter).

I also am looking for a privacy screen. Mine is a rooftop situation. I am fairly well screened to east, south, and west by other buildings, but the north side of my garden faces one of the main drags in town. It is on top of the first floor, wide open to a large parking lot so cars can see for about two blocks back right onto our rooftop "patio" Legally we are only able to put up a wrought iron fence (must be metal). Can't be a privacy type fence, it must be open rail. Well it could be, but we would have to hire a structural engineer to determine wind load, blah blah blah to pass code. I'm trying to come up with something affordable since it is 24 feet across that I need to screen. And since I have this lovely teenage daughter who would like to sunbathe up there, I don't want to be causing any auto accidents. :)

veggievicki - there are a bunch of rooftop gardens near where I work and I noticed that one has placed a series of large pots with columnar aborvitae around the roof perimeter as the screen. As the trees have grown, they have slowly begun to fill in the gaps between the spaces created by how far apart the pots were placed. I'm guessing they are spaced about 3 - 4ft apart. Of course there is probably a bit of a load issue, but then the pots were put right around the edge where I expect some main load-bearing beams should be. The trees have grown to about 6ft - 7ft tall now.

I'll check at the nursery. The hubby assures me there is adequate support for potted trees. He's a builder, so I guess he knows what he's talking about. Maybe. : )