I should add there is already a large deck behind this

Grass is very low maintenance actually. Invest in a riding lawn mower.

How much upkeep do you want? Where are you located? Do you use your yard? Want to sit out on a big deck/porch and enjoy flowers/plants? Birds, bees, butterflies etc? Or you just don't want so much to mow? Mowing is much less work-tho it's also much less appealing to the senses.

If you tell us what horticultural zone you are in, we can help. I live in IL where prairies and savanna were prevalent before colonization, so I have used mainly native prairie plants. Once established they take much less time than lawn.

Look for the books by Susan A. Roth: "The Four-Season Landscape; easy-care plants and plans for year-round color", and "The Weekend Garden Guide: Work-Saving ways to a beautiful backyard". Both stress planning and selecting plants for easy care. I think that both books are out of print, but your local library might have them. I also found them on Amazon, used.

Thanks for the comments so far. I live in zone 5 / northern Ohio. Also I really like a modern / minimal aesthetic

That grass lawn is about as minimalistic as it gets. Invest in a comfy riding mower and enjoy mowing twice a month. Treat yourself to something special afterwards to keep yourself motivated.

Actually organized, systematic study and comparison of different types of garden spaces has shown that mown lawn is by far the most labor intensive option. Here on my place for instance at this still rainy time of the year I could mow my somewhat large lawn about every third day if I were trying to keep it constantly at a typical height.

However if you try to convert half of your park like setting to beds that will definitely involve planning, upkeep and expense - if you are not passionate hobby gardeners now this will surely backfire on you.

The easiest would be to hire a lawn service but paying to have that big of an area kept up would definitely add up.

A lot.

For instance when I was paying to have my smaller area of lawn than yours mowed it was $60 per ~15 minute visit.

It is not stated where in the picture your property ends, but it looks like much more than one acre. Where you are going to cultivate, a mowed lawn, but not a 'fussed over' one, is going to be the easiest way to maintain the most square footage. But there may be areas more distant from the house where you choose to let the ground literally return to nature and nothing could be lower maintenance than that since, by design, you are doing nothing but ignoring the space. But before doing that, keep in mind that any kind of weeds or weedy trees can move in. You might consider a semi-controlled nature instead where you plant some trees, possibly the kind people would not ordinarily choose for a lawn, such as nut trees -- black walnut and such -- by seed for low cost. There could be a harvest that interests you in future years. Create distinct boundary edges where mowing stops and nature starts in a manner that looks good from wherever you are most likely to view it, as you would mainly be creating the future backdrop of a view.

Great suggestions!

If you’re not a passionate gardener and want to get rid of lots of that lawn maybe go for an arboretum approach with a selection of evergreen and deciduous trees that are low/no maintenance in your area and plant them out in the lawn. As they mature and shade out the lawn you’ll end up with a more naturalistic ‘forest’ type effect.

Getting the plant material and watering, staking, removing lawn, to get them started and established will be the majority of the labor needed and will all be in the first couple of years.

Yours is not an over night project. It will take years to accomplish your goal...which is to create a more naturalized yard. Creating beds, planting perennial ground cover, perennial flowers, etc. is a long term project. A suggestion might be to create two sections to your yard with an ornamental fence between them. The part close to your house is more “tame,” and the back part is left to naturalize with mowed paths through the understory created by your trees. Just a thought.

If you think rocks gardens and planting beds are less work that grass , think again, My suggestion is get a landscape designer to help with what you want to achieve and honestly what you have is the cheapest way to go