Not really OT, as the OP asked for some inspiration. Here's a pic of our foyer looking into the den, where the original owners had a grand piano, and entertained frequently. He was a jazz buff who composed his own works, and once met Sinatra. The great room and foyer are all 3/4" alder. The acoustic ceiling is original; it's hard to see the detail in it in this pic. I did grasscloth in the den with cheetah carpet, 'cause as a displaced Chicagoan, our unofficial motto was "if it's worth doing, it's worth over-doing." Most of the tile is the hand-cut hexagonal stuff, but some have hand-drawn designs in them. We found another 40 or so extra tiles in the backyard. This reminds me that I need to scrub the floor. Here's another pic with our Great Date hamming it up for the camera.

While it will shrink your side yard, you might consider planting a couple of rows of cedar trees or other evergreen trees or shrubs )that keep their leaves year round) to create a "green fence" between the railroad track and your home. Not sure it would help with the sound but it certainly wouldn't hurt. After you plant the first row, plant the second row with those trees/shrubs blocking the view of any space between that first row.

Frank Lloyd Wright lived in the 20th c. and this house owes more to him that the atomic-plastic aerospace era most people associate with MCM, and therefore want to paint everything rocket ship gray and kool-aid lime plastic unless they are looking at a colonial. You are right not to want to paint the brick. An unpainted wood front door with glass would be optimal and ditto if you can afford natural unpainted wood garage doors that might be handsome, otherwise go with weathered grays. It is really quite impossible to offer suggestions about the rest of the trim with the awning up there, and the overgrown hedges under the front window. The sharply trimmed hedges are appropriate to the house but they need to be trimmed way back. Do that first and then see where you’re at.

changing the garage really makes a huge difference in overall style when they're front facing like that. my house is posted above (the green one - please ignore the horrendous lawn). it wasn't very MCM looking from the outside, and the new door made a big impact. also, so much more light inside my garage! the style that I chose is a little different -- the windows are extra skinny (for some reason I can't find many examples of that online). if you're interested, the brand was Modern Tech style "BFL" (brochure here). but what you have now is not bad. you could paint them to match your front door for now and concentrate your efforts on other updates. also, regarding black soffits making the house darker: I read that too. exterior surfaces can make a surprising impact on how much natural light bounces into the home. it would be a pain in the butt, but you could temporarily tack up black paper above a few windows to see if it's really all that noticeable or not.