Where are you? I know you say zone 7, but that covers a wide range, and some things do better in one end or the other of the range.

How high? How long?
Do you want an evergreen? Broadleaf or conifer?
What are the soil conditions?
How much will the front plantings cover it up? Will it still get full sun? Will you have good access for shearing after the front plants reach maturity and they are rubbing against the fence?

I would tend to do a mixed border with conifers in the rear and flowering shrubs fronting it. Even if you choose 3 or 4 and repeat them, if one dies you aren't left with a gaping hole that needs a specific size of a specific species to repair. And you won't have to squeeze in to do biannual shearing, either, which could turn into quite the ordeal as everything grows.

You could design quite a nice little vignette if it is a smallish area, or a stunning run if it is larger.

It is my opinion that vines would only contribute to an unkempt appearance on what you've described as a "mish mash" of fences- they just don't behave. YMMV.

I should have mentioned:
-6 ft. tall fence
-Evergreen broadleaf would be nice but conifer would do nicely
-Soil is an ammended mix (soil is naturally sandy)
-I will try to plant so that I can still get in there w/shears
-We're in southern New Jersey
-It's a pretty large area (about 48' x 64')

cearbhill: Good point about replacing specific species. I hadn't thought of that. And I did just rip out an example of a vine that just wouldn't behave: passiflora incense, so you're probably right on that, too.

Just a few that come to mind that I happen to like--

1. Boxwood is very formal looking and takes kindly to shearing.

2. Holly. Just love these and in S.Jersey they're practically weeds.

3. Yew They are very common (but there is a good reason for their use as hedges).

4. Photinia "red tip" They grow very fast once established and are quite "shearable". (In the South they are prone to various blights but you're north of the problem areas for them.)

njoasis,

Thanks for the advice. I'm leaning towards American Boxwood or Steed's Holly, whichever grows fastest (I'm trying to get it to 6 ft. asap).

I like photinia a lot, too, but I'm looking for a neutral green backdrop for other plantings. And I'm planting yew in deep shade in the front :)

I am sure your area is warmer than mine but I am growing a climbing hydrangea in full sun (from sunrise to sunset). In fact it is also in an open windy site, just an old bare apple tree frame for the vine to grow up on. So far it is doing just fine. I keep it watered and mulched though, maybe that helps.

Cindi

i have no idea if zone appropriate... but the autumn clematis is highly aggressive.. and fragrant.. beginning to flower about now .... better be able to enjoy the flurry of bees though ... one plant covering 10 to 30 feet per year .... in my zone ...

and someone gave me a vining honeysuckle .... again.. summer fragrance... and i SEEM to recall .. something that will cover a fence.. or small building.. lol ...

again... just suggestions.. i will leave it to you to do the research.. or others to warm you away ...

these .. or these sorts.. literally cover the fence... then you can do shrubs or conifers in front ....

good luck

ken