I like your black roof idea. I would continue with the black on the window trim. As far as applied stone on the pillars, not crazy about that but would love to see rocks in the front with grasses. Not formal, more like this picture.

here's are pics of a houses similar to the one you posted.
Maybe they will give you some ideas

with stone

No budget? I could see stone on the center of the house running up through the day light where the entry door is to the 2nd floor lining up with the dormer.

If your next roof will be black or charcoal, I'd take that onto the columns and then face the home in stone. These houzz pics hint at what it might look like:
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HI --- I am not so sure you need to do that much with having stone on the pillars and so on . If the roof needs to be done , then think about a metal roof . If your changing the roof just to do a color change , that is unnecessary . Just paint your trims for now , maybe go into a charcoal that has a green undertone . What your beautiful farm needs the most, is just some landscaping. Like trees to frame the house . How about a random collection of aspens or birches and a few evergreens for winter interest . The white bark of the aspens and or birches would look great against the dark trims of the house . Maybe move in some big rocks in groupings and other bushes and low growing evergreens like junipers and yews .Lilacs or any other flowering bushes.

You can look at pictures all day and see hundred different possibilities, but go for a drive in a historical district and see the color choses in person. When you see it you will know. And if you see people outside, don't be shy about asking the color, most people are proud of their homes and want to share. My aunt painted her home a couple of years ago, she lives in a very rural area, a month after painting it she found a note in her mail box asking what color names and brands her homes paint colors where, along with a self addresses stamped envelope. The people were visiting family in the next town and had went for a drive to see the fall colors, they actually lived in North Carolina my aunt lives in Arkansas. One year later she received a picture of a beach cottage, with her paint colors, on the back of the pictures it simple said, Thank You!

definitely need to make that front deck look more like a porch. I find the columns oversized already, if you add stone to them they will look even heavier. Is the stucco finish removable, if so you could reface them in a composite material that looks like wood to give a more traditional look. If they are a solid cement they could still be refaced to look like wood porch columns but would still look a little too thick. You also need to add a floor to the under column area to make it more porch like instead of just a continuation of the side walk.

I wouldn't do anything to the house until you get the dark green roof replaced with a charcoal. I love the columns as-is -- definitely should not make them wider/larger. With a charcoal roof, I'd do white trim with light gray walls. With the dark green roof, I'd do taupe walls with white trim. I do love the classic black shutters on taupe walls though, so black trim with taupe walls and a charcoal roof may look nice as well (I've never personally used black on house trim before -- I'm not that brave!).

As a color analyst, my first inclination is to bring the house facade out and send the pillars back in (which currently take center stage). We can do this by adding texture to the walls and blending the pillars through color. For example, try a full stone facade on the front, a 1/2 wall stone on the sides and a "simply taupe" color for the remaining exterior including the pillars. A "deep taupe" roof and trim/exterior window trim will create dimension. Interior window trim + railings would look good in a "white sand." Bringing the stone out the front walk and extending it to the driveway will tie in the garage. I din't know how the colors in this will appear on your computer, but you can use the info to see what they look like at the paint store. Good luck!

One more thing! I almost forgot about the door! You can use one of these colors, but a contrasting color is always fun and welcoming. Historically, a red is a go-to. This "mineral red" would blend well with this palette.

Every thing austinthea said! Plus a black or dark charcoal roof!

We have a 120 yr old farmhouse and were in the same dilemma. Ours was an awful medium blue with gray trim with a lattice framed porch when we got here and needed to be redone immediately! We rebuilt the porch with picket railings as had originally been there and painted it a creamy beige with sage green trim and accents of pilgrim brick red. The roof is black shingle now but we intend to do a dark gray metal roof when the time comes. That way we can change the color of the house in the future without staying in the greens. Hope it helps, we love our color selection. Sherwin Williams has a site that you can try out colors on your house, check that out, I think you upload a photo and then you can paint on the website.