Everything sounds very neutral, so if you are not planning on reselling anytime soon or are willing to repaint it if you do, I would go with a nice, but not too bright or jarring pop of color.
I agree with @JLeslie that stains are a great option instead of painting. They are stunning and have a more subtle effect than solid paint. They are also more durable than paint, which tends to get damaged when walked on. Here are some stain color samples to give you an idea of your options. I’m personally a fan of the deep, rich colors, like teals/blues, purples, and brown-red tones. And if you wanted to stay more neutral, the dark greys/browns and blacks are also beautiful and would stand out in their own sense.
If you want to stick to lighter neutral tones, I would opt for paint instead, because the light stains come out looking slightly off and unfinished, in my opinion. You can also achieve much lighter hues with paint than are possible with stains, for obvious reasons.