How do I set up PBR-correct sunlight?

I’m currently working on creating a realistic looking scene, but I’m struggling with nailing down a good looking light setup. It’s an indoor scene, with sunlight coming in from large windows.

While point and spotlights use lumen, directional lights simply have an intensity value. What would be a correct sunlight intensity?

I can’t seem to get it to look good, I land on one of these two cases:

  1. A bright sun will make the specular reflection on the floor much too bright
  2. A darker sun will make the specular reflections look good, but the indirect lighting in the room is way too dark

If I enable tonemapping, I get intense brightness changes. If I look at the sunlit areas, everything else goes near dark.

The floor is just about the only thing I’m sure is set up correctly, since it’s a PBR calibrated, scanned texture.
I can somewhat make things better by increasing indirect lighting intensity, but it feels like I’m going to ruin PBR as soon as I start adding unrealistic intensity tweaks like that.

Are there any guidelines to setting up things like this?

I’m having a similar issue, object materials set up using PBR values but the sun seems to bleach them out if it set to any value that lights the scene brightly. Did you get your scene to work? If so, what values did you use for the skylight?