I have been told cedar is not healthy for ducks.
Some use stall mats which can be hosed off.
Be sure there is a little bit of slope, and that the downhill side can be easily raked out or covered. If you have a choice, well-drained soil is best.
Duck manure is excellent fertilizer and compost material. In my run I have a few different substrates. There are areas piled with straw for resting and noodling around, areas with sawdust that begin to act like flooring and once a month or so need to be scraped out and replaced, and the area under the swim pans has pea gravel and drains into a small channel that runs to the grape arbor, thereby watering and fertilizing the grapes in one swoosh. I do need to rake off detritus from the pea gravel a few times a year, and make sure the drainage isn't obstructed with organic material.
I have found that dry oak leaves neutralize odor very well. Also, fluffing the material, adding fresh carbon-heavy (straw, sawdust, coir) material regularly really helps.
When I do the occasional muck-out, I carry that material over to the compost to supercharge it.
I tried sand in one area for the ducks. In my case, it rapidly began having that dirty sock smell that heavy nitrogen material gives off, and that is when I began covering it with pine shavings. So the sand drains well, but the shavings catch manure and nitrogen and help neutralize the odor until the occasional cleanout (again, onto the compost pile).
Their house has over a foot of shavings, which get stirred daily, and I top that off with a few inches of nice dried straw, which gets replaced every three or four days. A friend stuck her head in the house, took a deep breath, and said, "wow! It just smells a little earthy - very clean!" I would sleep in there (on a blanket, natch).