Hello Neighbor!

If I were you, I'd invite someone from your county extension office out for a cup of coffee ... to give you some ideas.

Native plants and prairie grasses would be the first plants to consider on any areas you do not want to mow. I'd be looking to cut that mowing way down to say ... just an acre near the house and out buildings.

Trees, berms, windbreaks and flower beds would also be high on my list.

Of course, the amount of money and time you can commit to changing your place is a key factor.

I keep reducing the amount of grass I mow by adding and enlarging my flower beds. The mix of plants in those beds also changes from year to year, as I seem to always be getting new "ideas" on what I want to grow.

Hello, I live very in Minnesota close the South Dakota border so I may be able to help you out. I can't say much about making your land profitable, around here that usually means leasing your land to a farmer to grow corn or soybeans. However you can invest in making your land benefit you and the environment, which may not make money right now but will benefit future generations.
First I would have to agree with what iowa50126 has to say about talking to someone form your local extension office, they can give the best advice and connect you with other people who can help. Any part of your land that you are not actively using should be planting in native prairie plants. Chances are the "wild grasses" you mentioned are actually European grasses like Bluegrass and Smooth Brome that have replaced most of of the prairie grasses in the region. Read books or search for websites about prairie plants and learn how to identify prairie grasses and flowers to see what you have growing on your land. If you do indeed have a true prairie remnant with American prairie plants and grasses you are very lucky and should learn how to keep it healthy. You should not have to mow any prairie except for in spring or fall to chop up the thatch to help make room for next years growth. Normally fires would periodically burn off the thatch but you would need permits and a fire crew to do a prescribed burn for a large area. A healthy prairie restoration provides habitat for many kinds of wildlife, like pheasants, butterflies, birds, bees, etc. It also filters water, builds soil, and even helps take a lot of carbon dioxide out of the air and stores it in the ground as organic matter.
Planting trees and shrubs will help catch snow in winter and slow the wind in summer as well as provide food and shelter for birds. In my area Bur oak, Hackberry, Cottonwood, Honeylocust, Basswood, Silver Maple, Colorado Spruce, Black Hills Spruce, Eastern Redcedar, and Ponderosa Pine are are the most dependable trees. Good shrubs to plant for windbreaks are Smooth Sumac, Common Lilac, Wild Plum, and Chokecherry. Fruit and nut trees are a good investment. Apples, apricots, wild and cultivated plums, sour cherries, chokecherries, pears,and Black walnuts do well. Other fruits are good too, Raspberries, strawberries, currants, and gooseberries do well. Plant some rhubarb and asparagus too.
Grow a vegetable garden, and learn how to garden organically Rotate your veggies, plant vegetables in a spot one year, then a cover crop lie oats, wheat,or sunflowers to build the soil the next year, then a legume like peas or beans to add nitrogen to the soil. Be sure to mulch everything with straw, compost, grass clipping, leaves or whatever you have available to keep the soil cool and moist, and to add organic matter.
Plant lots of flowers and shrubs to attract bees, butter flies and birds make sure to mulch everything so it need less water. Focus on planting mostly American native flowers and plants, they are the best adapted to growing here and benefit wildlife the most. Keep in mind that many "wildflower" mixes in stores are mostly non native plants and often contain weedy aggressive plants.

Here are some websites for you
http://www.sdconservation.org/
http://www.bellmuseum.org/distancelearning/prairie/
http://www.bellmuseum.org/distancelearning/prairie/fieldguide/index.html
http://www.ag.ndsu.edu/pubs/ansci/range/eb69-1.htm
http://www.ext.nodak.edu/extnews/askext/fruits.htm
http://www.gardensites.info/states/sd.htm
http://www.ag.ndsu.edu/pubs/plantsci/landscap/h322w.htm
http://www.ag.ndsu.edu/pubs/trees.html
http://www.ag.ndsu.edu/pubs/plantsci/hortcrop/h1106w.htm
http://prairieroots.wordpress.com/
Hope that I gave you some things to think about!