You needn't plant a hedge. Think about plant of various sizes such as floribunda roses, lilacs, forsythia, etc.

How quickyly do you want your privacy and how much yard are you willing to give up and also how much do you want to spend$$.
Since there is already an existing fence, one choice would be to install a taller fence across the back. Planting smaller shrubs and perennials and such in front to soften the look of the tall fence.
Then there is the traditonal row of arbroviatae - ( I really dislike) but that will work. They will need a bed space of about 6ft deep or more for the length of the property line. They will need care, water and they will need planted with space in between each plant - enough room to grow. Not total privacy until they grow together. You can buy bigger plants, but then the cost increases. Oh I forgot, if one dies after about 10 years - you will have to find a large plant that matches the rest so the row looks continuous.
If you have more room to plant ( bed depth 8 plus ft)you can create a nice border of small trees and large shrubs, mix in a few tall conifers for winter interest and you will have something nice to look at, but still you may have to wait a few years until they grow, for total privacy. The cost will depend on how many and how big.

So the answer to the question, it depends on what you want and how bad you want it.

Mike
PS What is your zone, that will help for more specific shrub names

Remember that anything you plant is going to cast shade. If it's a solid row, it will be uninterrupted shade, and if it's a solid row of evergreens, it will be year 'round uninterrupted shade, which will extend farther as the sun moves lower in the sky autumn, winter and spring. The higher the row, the longer the shade it will cast.

It's hard to tell from your photo, but it looks like your neighbor is to your south, so you'll have a considerable shady area there. Are you willing to deal with that? If I'm guessing wrong, how will your neighbor feel about that and are you willing to inflict that on them?

I strongly agree with those who say you needn't plant a hedge. A few carefully placed trees and shrubs in the primary sight lines should provide you with the sense of privacy you need, yet will cast only interrupted shade in the area.

Thanks everyone for your suggestions! In response to plantman, getting a new fence isn't an option mostly b/c of money but we also really don't want to do anything that will seem rude to our neighbors. We also don't really like the whole row of arborvitae. I was originally thinking of doing a mixture of shrubs and trees. We already have a Cleveland Pear (?) tree back there so we were going to get 2 more of them. After that we're a little lost. As for space my husband has dreams of our boys playing full on tackle football back there so he doesn't want to lose too much lawn. I could convince hime to lose 4 to 5 feet. Thanks for your help!

I had a similar problem when I bought my home, but the sight lines extended across three lawns. Talk about a goldfish bowl! And was exposed from 2 sides too, not just one. So, I had a crew bring in enough dirt to make mounds, or berm-type raised beds across the two side lines, then planted Virburnum, some tall and narrow evergreens, one swamp oak, etc,. That was 8 yrs ago. My yard is now a bird sanctuary and totally private. The shade increased quite a bit, but I planted mostly smaller trees, like River Birch, Acer Griseum, Sentinental Maple, (which I am not fond of), and understory shrubs.

Truthfully, I felt the wonderful sense of enclosure almost immediately.

The mounds were straight across the lot lines, of course, but swooped in and out to varing widths within my yard.
I will happily send you photos of the before and after, if you want. The virburnums, especially, were nearly instant privacy shrubs. Most are "Chicago Lustre", but for scent and beauty, plant "Korean Spice". There is a lovely summer "lilac' tree too, that isnt some giant. Just right for a small yard, and very good scent in early July.

One amazing thing about enclosing ones yard...it actually looks bigger! I don't know that much about spatial views to understand why that is so, but it IS so.

I hope you just go for it. Weather its just the back yard view, or all three sides, you will love the results.
Pondy

Pondy, that sounds beautiful! I'd love to see some pix if you don't mind sharing. The fishbowl is a funny reference. I'm going to have to use that too! Thanks for the advice!!

Honestly, I think you need trees, not shrubs, as you don't need the mass at ground level but rather above fence level. Almost any deciduous trees will do but obviously they have different features and characteristics so it is worth doing a little research on what you have available at local nurseries. Personally I would want a variety of sorts that offer some contrast, not a repeating row.

KarinL

Here's a site that might give you some ideas: fast-growing-trees.com

I am hemmed in by my neighbors and ugly chain link. I have found that some of the best privacy foliage comes from SMALL trees. I have a japanese maple, japanese snowbell, and musclewood/blue beech (Carpinus carilinia) althought I think they commonly sell european ironwood at the nurseries too. Redbud and kousa dogwood and Amelanchier/Serviceberry are other popular choices.

I think we're going to get another cleveland pear and see what else we can find. Is there any rules or suggestions about design. What tree/shrub should go where? I've never done anything like this and am desperate not to make a design mistake.

One person's "design mistake" is another person's brilliant solution, so don't worry about what a designer might think of what you do. The key is to get the blockage provided by the foliage where you want it, giving each plant room to grow to its eventual size, to whatever extent you wish to let them grow vs. keep them in check with some pruning.

Plants are quite adaptable, and the conditions you have there should suit almost anything you'll find at the nursery. Spend some time reading the plant tags, and if you aren't sure or there isn't enough information, write the plant names down and go home and look them up on the internet or look in a shrub/tree book to find their eventual size and shape, and what their features are through the seasons. If you find you don't get it right the first time, you can move plants in a subsequent spring or fall for probably three or four years.

Since you have some shrubbery already you'll be aware that deciduous trees will still leave you exposed in the winter, so if you don't want that, you should include at least one evergreen.

KarinL

Thanks KarinL. I'm just going to go for it. It's been fun so far trying to figure this out. Thanks everyone for the input!!!!

We have a partial taupe vinyl fence. Where the fence ends we have planted a 5' row of Rose of Sharon. In a past home we used Rose of Sharon and created a blooming summer - fall fence. It was not costly and it grew quickly. Find someone who has rose of Sharon and take some roots. Plant rows not too close together and wa - la in a year or two..pure privacy and flower blooms everywhere. Just need to prune to keep shape and height. Good gardening ~

Just a thought~
If you want plenty of space for your kids to play, how about putting privacy shrubs around your patio? It looks lovely and could be a wonderful private sanctuary for less money and time....
Just thought I'd toss that into the "thought pool"! Have fun!