I appreciate all the input on pouring a concrete run. I just know my land and how soggy it is with all the rain and for me, concrete just makes sense. One other observance... my chicks are currently in our garage in a 4 x 8 coop which sits on a vinyl remnant. The garage floor is concrete obviously. I watch the chicks every day and they scratch and peck through the shavings on the vinyl. That is their favorite past time to scratch and peck. I get it. But, I can't help thinking that if pecking the vinyl on the concrete was too hard on them, I would see signs of distress...which I haven't. So at this point I'm resigned to pouring concrete for the yard. If we go on vacation, I would hire the neighbor kids to collect the eggs, let the chickens out and make sure they close the yard gate at night. So given my particular circumstance, I just don't see any downside to a concrete yard as long as I let them free range during the day.
Again, I posted my plans for input and I do appreciate the voices of experience and I'm taking all the advice under consideration. I just happen to live in a part of the country that gets a lot of rain 8 months out of the year and I need to take that into consideration.