Here are suggestions for a simple scheme that keeps some lawn. The first thing I would do, though, is bust out the end of the walk (where it meets porch) or maybe the whole walk, and redo it, adding space and width. A skinny walk with little space at the porch makes the whole house look cheaper. If breaking out and redoing is not possible, then find a way to patch on some extra space.

I second the concept of a "relaxed, old fashioned garden that says “farmhouse” - yes with grass meadows. With 140 acres you will have plenty chores. There is no need to make the grounds around the house into another constant chore, unless one of you is an avid gardener, well then we can't stop you. Some ideas to ponder: A farm house landscape needs a legacy tree, that single, large, perfectly shaped, mature, deciduous tree. You have only shown us one view of the land. That tree might belong on a different side of the house. Someone has to plant that tree first. What is the state tree of Missouri? What is your favorite big tree? Give it the room to live to be hundreds of years old. Be the people who planted that tree. Piet Oudolf is a great source for inspiration. His work is based on very intentional layout of plants. I think you could go with a more specific to your place, natural grassland meadow and still mimic Oudolf very well. A grass meadow is probably the best way to live with deer. Plenty forage and color for everybody. Paths are most important in this kind of landscape to give it intention. Mowing would be easiest it seems and just done regularly with the areas kept as lawn. You can add a touch of modern or formal with sculpture placed in a meadow. Could even be done in plants. Picture this off in the distance from a primary view from the house, rising from the meadow, a row of columnar evergreens standing alone, closely planted to make a green wall or hedge shape with a single Lime Light kind hydrangea given the room to grow to its massive self when left alone. First thing I would think about in laying out your landscape is the traffic patterns of people and the machines you will be using. If you do any regrading or bring in top soil think about grading the paths first and making them rideable in ATV's. That will help tell you where the gardens go. There is joy to be found out there.

I second emmarene's comments. Especially the lighting. Also, consider adding some "ooompf" where your steps meet the curb. Is there a way to flare out the walkway at the curb, to give guests more landing area? In addition to flaring the walkway, I'd add a nice curved flowerbed on either side, in an arc from the street all the way up to your retaining wall. Daffodils for cheery yellow in spring, maybe a leadwort/plumbago groundcover for blue flowers the rest of the season. This would blend in to your grassy natural landscape. Which I would "tame" mostly by adding flowers -- iron weed, joe pye weed, milkweeds, native yellow daisies, that sort of thing.

Oh wow… what a house. I would hire a landscape architect with experience with MCMs, even if you do the labor yourself. We have a sloping small backyard (in LA), but had someone draw up some plans based on our rough ideas. He also let us know what we could and could not afford on our budget. I thought we could afford a deck using certain material (i looked at material pricing plus estimated labor), and he said that is NOT in your budget, hahaha. He was also very helpful in designing it for us to add stuff later easily, whether underground or above ground.