need fast-growing bushes for privacy

Our house is on the corner in a neighborhood with a fair amount of pedestrian traffic. I'd like to create a more private space by planting bushes around the edge of our property. Problem is, one side of our yard has a pin oak, an elderly but lovely Japanese maple, and some azealas, along with various unidentified shrubs. I sure don't want to damage their roots - Is it a bad idea to to plant a row of tall bushes, say, a foot or two away from these existing trees and bushes?
Also, what bushes would grow fast enough to make the yard feel more secluded without having to wait 5 or 10 years? Am I being unrealistic here?
I'm in zone 6.
Thanks in advance for any advice.

Can you post a picture?

Great idea, I'll try to take photos tomorrow.
Thanks!

Actually once there are leaves on the existing bushes, it fills in quite a bit - leaving only 2 or 3 'bald' spots where I really need to plant new bushes. That simplifies things a bit. Of course now, at the end of winter, there's no foliage yet.

I'm drawn to Cotinus, Rose of Sharon, and Rhods - these can get pretty tall which is what I want. They seem like good bets because I see them in neighbors' yards. The soil here is pretty acidic.

Smokey SC, I'll try to take pix today. Thanks.

I grew up in south Jersey (which may have different soil than you). Rhodos and hollies grow great there. Rutger's has an interesting holly named Ilex 'Red Beauty'.
http://rutgers-technology.blogspot.com/2008/10/holly-red-beauty.html

Have you considered Pieris japonica? This is a link to the cultivar 'Mountain Fire' but there are many other interesting cultivars. This isn't a fast grower but it's a very nice plant.
http://davesgarden.com/guides/pf/go/59720/
I'll bet it would love your sandy, acidic soil.

Of course, none of these ideas may work--I Just wanted to throw out some ideas.

Some of the junipers will grow fast and won't mind being stuffed in.
also, that ilex is a good idea.

If you want privacy in the winter also, keep to evergreens.
Kalmia, rhodo, and azaleas won't grow fast.

Some of the arborvitae might do you well, there are a few that
grow relatively fast, bushy and evergreen, and inexpensive.
Sheri

In my area landscapers would use Portuguese Laurel, English Laurel, Photinia, Ceanothus, Berberis and Taxus for evergreens. For a shorter hedge I'd use Leucothoe fontanesiana 'Rainbow'. There was no mention of a height.

Thanks everyone, this is extremely helpful advice!

Smokey_SC, here are pictures of the yard showing the gaps I want to fill in. Two pix were taken at ground level and one from a second floor window. You'll see the area is full of underbrush but there are big gaps - makes me feel like I'm in a fishbowl when I sit in our back yard. I don't much care in the winter, but in spring-summer-fall I would like a more private feeling.
Whatever grows fairly fast would work. I particularly like Rose of Sharon which does well around here.
I'm a rank novice so I'm open to suggestions.

I guess I can only post 1 photo at a time? here's another.

Trying again to post the 3rd picture.

If it were me, I'd do a Taxus 'Hicksii' hedge, failing that, a Thuja Smaragd or Pyramidalis hedge. That'll give you evergreen hedging and privacy.

thanks for the suggestions!

I have forsythias for privacy. They get huge and fill in a lot of space quickly.
There are smaller varieties now that do not take up as much room. What I like about them is that you can prune them and make new plants so easily.
And also, after the early display of yellow, they are just green and blend in easily. Here in zone 7a they have a lot of the leaves throughout winter also.
The one pictured fills a lot of space in my front yard.

Rose of Sharon and forsythia are deciduous however and will give little privacy in the late fall, winter and early spring.

My early blooming forsythia is a picture taken March 3rd in zone 7a. It is about ten years old and has a lot of branches that are pretty dense even without green.
My Rose of Sharons lose every leaf down to the bare branches.
Maybe a holly of some sort, but they are so slow growing, you would have to buy a big mature plant.

There's an idea - Holly. There's a hedge of variegated English Holly down the street from me that looks ok and you can trim the hedge in winter and use the trimmings for wreaths, etc. I believe English Holly is ok in your zone?

This is a link to a company that I ordered from not to long ago. They are in our 'Garden Watchdog' listings also. Wonderful information about different privacy and fast growing tree suggestions.
http://www.evergreenplantnursery.com/Evergreen-Privacy-Screens-s/42.htm
I hope you find it useful.
Pam

jasperj, Portuguese Laurel is used a lot here too, that what I planted last year for a nice tall hedge. A landscaper that help me with other parts of my yard suggested that I incorporate a vine in the area too because it's fast and cost efficient. A kind of layering effect so that you see and the different plants. A sturdy structure would add interest year round, and would probably add value to your house.

Thanks,
Kristin