You need some much taller trees and shrubs to help the tall house fit better into the landscape. Go to your local nursery and ask if they have a landscape designer on staff. For very little money, they will put some ideas together for you, which is usually matched with a discount for the plant material.

I agree with the tree - do you think it should be some sort of evergreen? And what do you think directly in front of the porch?

I would consult with a local nursery for the tree question. You have to ask yourself do you want green all year? Do you want to sit on your porch and watch the tree sway in the wind and then rake leaves in the fall? Smile. I would plant the far left space first with the tree and ornamental grass. Remember to pay attention to how high the grass you buy gets. They can go 6 feet tall. You can do all of this in the early spring. Live with it for a few weeks and then tackle the front. You will have plent of time through the summer and even early fall. There is a plant called purple smoke bush that is really neat. Check that out for front of house.