Wood chip mulch makes a nice background for specimen cultivation, and can be had pretty cheap, by the truckload.
But before you spread it on, you need to kill off everything that is growing there now -- lawn, weeds, etc. -- so that it doesn't come back up through the mulch later.
Simply spray the whole lot with Roundup, once its all growing (say in a couple of weeks).
Two applications, spaced a week or two apart is even better, to make sure you got everything.
Then you need to figure out what sort of specimens you wish to cultivate.
For such a large area, some mid-size conifers and Japanese maples might be the way to go, if you can manage the attacks by various animals.
Good luck !

Dear Sally,

How about this. Turn that portion of the lawn into a wildflower/prairie garden. I've been doing some experimentaion with wild flower gardens and I can tell you the idea of mixing wildflowers with grasses look fantastic. The wonderful thing about wildflowers is these are perfect for beginner gardeners. And it nicely blends in with a stone farmhouse. Simply sprinkle seeds at random and watch it grow. And in order to prepare that area, you can dig out the lawn and invert the grass to kill it, weed and all. Add a little top soil and then sprinkle all forms of wildflowers.

To give you some inspiration, check out this site: http://www.millenniumpark.org/artandarchitecture/luriegarden/plantlife/seasonal/

or check the works of Piet Oudolf & his famous Wave Gardening method

I would not recommend spraying such a large area with Roundup. While it is not nearly as toxic as many other pesticides, it does have some effects that are possibly causes of concern. It has been shown to cause abnormalities in fetal development in rats and humans and possibly other mammals. It is considerably more toxic to aquatic life and amphibians and one study shows it affects earthworm populations and nitrogen fixing bacteria. In small doses, over small areas, for particularly tough weeds, it's a good tool for the job, but widespread spraying is not a safe or proper use of the product. If you are in Quebec its use is banned for cosmetic purposes. You can turn over the grass, as Ianna suggested, cover the area with landscape fabric or something else for two weeks, or just till it all in. If you till it in, be prepared for a sudden explosion of weed seed germination. Tilling it a couple more times a week or so apart will kill off most of those new sprouting weeds, and you will have rid the soil of much of the dormant seeds and you'll have fewer weeds in the long run.

There are several planting options for the area, depending on what you want it to look like. If you want it to resemble a lawn, you can spread clover seed. Clover makes an excellent lawn for a low to moderate traffic area, it does not need mowing, it needs less water than grass, and it improves the soil, in case you want to do serious gardening there at a future date (and your horses will probably eat it if you want to put them back there).

Wildflowers are great and look beautiful. Don't buy super-cheap mixes - get a nice one with a good mix of seeds.

Some sort of rock garden would be nice and many of those plants are very low maintenance.

BP

A belated thanks for your suggestions. Much to think about. My local garden center fellow tried a wildflower garden once, and grumbled that after 2 years it just looked like a mess of weeds, so he no longer stocks the wildflower mixes. I have been shy of trying a large expanse of wildflowers since. Mind you I like them well enough in the pastures -heck I even enjoy the yellow of dandelions in moderation!
Thanks again
Sally

It must seem daunting when you do get such negative feedback from a garden centre. Its too bad that he discouraged you from trying it out.

Tell me what you feel about gardening? Do you like to putter around in the garden or do you like a very low maintenance yard? Do you like casual gardens or formal gardens?

Hi Ianna
I like my veggie garden out back, but the flower garden and yard is second to the animals in affection and time dedicated. The house, being an old stone farmhouse, cries out for informal English country cottage style. I have minimal artistic talents, and my attempt at perennials looked like plants randomly poked into the ground (possibly because I randomly poked plants into the ground). I took an on-line landscape design course from Guelph University for 3 months to try to get a better handle on the basic principles. Found it fascinating, and have more of an idea for the shrubs and things around the house. I start my annuals for the annual bed and window boxes from seed with moderate success, but my attempt to overwinter geraniums and start slips was a total bust. The thumb is closer to the brown than green hue. It is this honking big piece of land in front of the house that has me really stumped. I have a visual demarcation where I think a landscaped portion should end...then the wasteland from there to the road. I hope to learn a lot from this site.
cheers
Sally