Time to line the coop - Mulch vs Sand: Need your input!

[TimonHens]

So what I have found as a newbie trying sand is that there is a difference in the 5$ all purpose sand bags between big box stores. Lowe's seems to have a lot of course grains in the mix and HD is a fiber and more uniform.
We have a poop board that gets a few handfuls of sand to sift through, and the fine stuff works better. The course stuff is in the scratch section and it seems a bit unpopular at the moment.
Now that it is getting cold, I am going to keep a close eye on it with a willingness to change my mind. Since everything is going to end up with a light layer of sand and straw no matter what I do ...

 

[Raymond Dean White]

Well, the coop is almost finished, and I have a brooder full of chicks! I need to get flooring material down next.
I was planning to line my coop with sand, and line my covered run with mulch (mixed size wood chips from a local tree guy). I was going to try to find suitable sand/gravel fines this week, but I read an article about lining with sand just now that raised some concerns about sanitation, respiratory issues, and chickens eating poops that are “breaded“ with sand.
Now I’m wondering if perhaps I could line the coop with the wood chip mulch as well?
Extra info: The coop has an earth floor, but we dug out a good trench and have a cinder block/concrete foundation. We built a poop catch under the roosts that I’m going to line with PDZ and scoop regularly. Lots of ventilation in the summer, with a system of windows that pop in for the cold months. I’m in central NC. We have hot summers, it’s a fairly rainy climate, and winters we sometimes have a few mornings that dip into the single digits, some winters we only dip into the 20’s.
Any thoughts are appreciated. I’m a little perplexed, as I’ve had a plan for a while now. I have been having a difficult time finding sand that is appropriate (not too fine, not too dusty, etc.) and now I’m wondering if a totally different flooring would be best anyway.

I've used sand for years but I live in a hot dry climate (AZ). Sand proved much less messy and was much easier to keep clean than either straw or pine shavings--though I use the pine shavings in the nesting boxes. Using sand I didn't have to worry about mold.