I did 20 all around. But I have white interior. I have no problem seeing through my windows at all. At night, all the interior lights are on, nav is on, it you can see through the front. Rear, you can't see through for shit from the outside. You can see out though no problem.

Personally, I think the rears became too dark with 20. Had I known it was going to be that crazy, I would have gone with something like 50% in the back, and 20% in the front.

I don't need to use the window shades at all now in the rear.