What meets your eye on first entering the house? Maybe try to use the threshold as a color transition to that?

In our current house, we have wood thresholds, stained. Our previous house was a Victorian twin that came with a threshold painted a hideous brown. The final set of paint colors before we moved included a Fine Paints of Europe dark green for the outside of the door, and a pale color on the door's inside. The latter matched the foyer trim. I also did our small front porch, its stairs' treads, and top of the porch railing in the same FPE green (and it LASTED beautifully BTW). White trim almost everywhere else, and the stair risers a rich purple. The stucco exterior was pale yellow.

I used the same FPE paint on the threshold so that, when the door was opened into the foyer, there was a flow from door to threshold to porch.

(Those colors were not historic by any means, but we wanted to match the other twin's yellow and white scheme with dark green door, and in the end, the house looked good from the street.)

Having said ALL that, when you described your house, I immediately envisioned a sort of dark red threshold -- and I don't even like red!

Ours was the same white color as the interior of the door. It looked great! Outside trim was white too with some red brick flanking the door. It's all gone now (new wood door and bye to brick) with this remodel!