They look pretty good as is. I thought they were already finished. I would go with a concrete gray. I liked Floquil Reefer Gray for a richer gray base on a recent project that had cut stone details, then weather it down with chalks for your deal I think. Just a bit, because you have so much area that you want to give it texture, but that's enough. The concrete and aged concrete are too yellow. Doesn't work for me.
I have a similar subterranean station project coming up. I thank you for your blazing the trail. Great to see you having fun.
