I like it as is, not painted.

If pinted I would do a pale sky blue

What light greige will the siding be?

I would want to complement the siding, so I may choose a green, blue, lighter or darker shade than the siding, I might match the ceiling to the furnishings.

I can picture this with the matching ceiling or a yellow or green ceiling.

I would leave it as is, and put a sealer on it. If you do decide to paint it, the light blue would be a very good choice, and would go well with your greige siding.

I like the natural,….

painting it light, white with a hint of sky blue will help lighten the interior of your home too.

If you choose a light blue paint color choose a LRV of 85 or above, you'll think it's white, but a hint of blue will show in the shadows. Suggested colors; Behr Helium, Behr Day Spa, BM Lily White, etc.