I think a stone veneer would be great. I used the Sherwin Williams Color Visualizer and painted your house a medium gray. I left your dark gray trim because I love how it works . Perhaps a red door with this combo.

AND here's a darker blue gray and I attempted to paint the door a light gray so you can see the light trim idea...not sure I like it as well:

Tsgierke, Questions for you!
1. You mention the 1920s in your post. Do you want to use the colors and style of the 1920s?
2. Are you under a budget? A brick or stone face add great expense to your project.
3. What look are you going for with your exterior? Traditional, contemporary, 1920s?

Your house is in the shade (from photos) which makes your house appear darker. You may want to choose a light to medium light tone as your grey currently darkens to dark grey in the current sun/shade.
Choose a darker trim to make the house pop. A brick veneer would give the house a cozy feel. Either red or wood door would pop. With the current grey, all you notice is the door.

Here's one of my favorites. This would look awesome on your house with the stone on the chimney. I would keep the house subtle and do your favorite vibrant color on the door.

Thanks everyone for your suggestions! We ended up choosing [Behr Atmospheric PPU12-15[(https://www.houzz.com/products/behr®-paint-color-atmospheric-ppu12-15-prvw-vr~15054299) for the main color. We'd like do a white trim, but still considering options for the door.

Do you know what is under the shingles of your chimney? You may have brick or stone already there.

Here is a picture how your house would be look with gray