Things that would improve appearance and/or function are: Add cheekwalls to the steps so as to keep soil from washing onto them, make lawn maintenance easier, and give a more solid, substantial look to the property. Increase the size of landings above and below the steps. We can't see it, but likely widen the walk that extends left of the door. (There's a good chance the large tree walk is too close to the house.) Raise the canopy of the 'Bradford' pear tree. Dense, dark tree foliage so close to the ground is obstructive to view, yard use below the tree, and looks oppressive. At the right wing of the house, continue the hedge around the side to connect with the main portion of the house. Below the bank of windows and in front of the landscape wall, create a colorful planting of annuals for ongoing display. Around the large tree, create a mound-shape shrub with multi-season interest. Remove the scruffy growth of large tree from in front of the eaves.

The birch was allowed to grow past young age with a horrible structure, especially for its placement directly in line with the house center. Were it mine, I'd either want it to reform, in spite of the fact that it would need to go through an awkward period, or I'd want it gone. It is the bottom limbs branching off at 4' above the ground that looks so bad. I'd remove the two lowest every year until it was reformed.

In the one comparatively close view the tree appears to have included bark which means there is a danger of it splitting apart at some point. On top of whatever else is not liked about it being in that spot. Agree the lace leaf maple in particular can't be "pruned to 2/3" without wrecking a valuable specimen.

Your windows are fine. Skip any kind of grid. And leave the arches alone-- they echo the gable peaks. Square transoms would look awkward. If you must do something, either remove the transoms altogether or see if you can get triangles instead of arches. A porch roof, like Beverly suggests, would be a major improvement both functionally and aesthetically. But landscaping instead of a tarmac desert will do the most to improve your home's curb appeal.