Thanks everyone, for the comments.
First of all, I am in Houston, Texas and the heat index here has already been at 105 for several consecutive days. When designing the coop, I figured my first and foremost enemy would be the heat, and designed accordingly. As it turned out, there is almost always a prevailing southeast breeze where I finally located the coop and so far, so good.....all of the chickens are weathering the heat, although on really hot days they are breathing with their beaks open. The floor to the roosting area pulls out like a drawer and is covered with 1/4" hardware cloth as a floor. This means I can wash away all of the droppings from the night's roost in about five minutes and return the drawer with very little fuss.
The taller structure, which I call the coop, is extremely robust and is as predator-proof as I know how to make it. The openings are covered with Poultry netting PLUS hardware cloth with firring strips screwed down over the exposed ends, staples, etc.
It's a work in progress, of course....nest boxes are being built and will be incorporated into the right side of the coop. Hardware cloth will be added on top of the existing poultry netting on the small run, and I am going to add a removable tin roof to the run that matches the one on the coop. I am also adding a 5' x 10' run which will attach on the end of the small existing run.
My problem right now is crowding. I designed this coop for six hens max, but wound up with nine and a rooster, so the additional run will be a huge help.
Thanks,
DD