this works for our area (predators: hawks, raccoons, possums, bobcats, coyotes, 
fox , cats, dogs, owls, and snakes)
All the snakes around here that would bother the chickens are too large to get through chicken wire, we have cotton mouths, moccasins, and rattlers as big around as your forearm *SCARY* dont have many rat snakes but the ones we have are too busy with field mice and also VERY LARGE) 
We use a small gauge chicken wire I believe it's an inch. "Rabbit" wire also called hardware cloth by the majority of people on BYC for the bottom of the run. We elevated our coop 3 ft from the ground (will be adding a poo board for our garden compost efforts) and have sealed all openings in the coop box itself to keep out the critters of the night.
(We just finished this today so the extra wires have not been removed at the time the photos were taken.)
All plyboard on the coop as well as the lumber have been weather proofed on the outside
COOP FOR THE EEs (3 months old 2 roos and 3 hens)
these are the roosting poles inside, we will later put in a nesting box or two for the girls when they start laying
I do not have any photos of our large coop. If you want to utilize the ground for a bottom this is how we did it.
We actually used a 10x20 portable "insta" (not so insta) car port from northern tools and around that put chainlink secured with rebar about every 3-4ft also secured the chainlink to the carport with 18ga wire at the top bottom and in the center. Then after that was secure we used a dog kennel door for the door. (chainlink was 6ft and so was door I got this from a crap shoot deal on craigslist paid 175 for a dog kennel and only end up with half the parts) We then put chicken wire around the outside of the chainlink securing along the way about 5 ft up the chainlink. then went on the inside and made an apron of chicken wire which I hand sewed to the existing chicken wire and chainlink with 24 ga steel wire. We put a layer of dirt and hay over that to help it stay where it was supposed to it tend to bow when you put it down. We also chicken wired the door and there is a wood liner in front of the door. We covered our coop with a 20x30 tarp and secured that tightly with MANY bungee cords gorilla  taped (its not pretty but it works lol) the front and back to hold our folds(the tarp covers all that is not covered by the chicken wire also keeps the breeze off the birds and works great for cross winds in the rain). The roosts: in the front end of the coop our rooster was frequently roosting on the bent rebar over the door so we added a roosting pole about 3 ft into the door....He stopped roosting there. lol. We built a self standing roost for our nesting boxes. It is made with several split 2x4s with a roosting bar on the end which is where the roo now roosts there are 3 cradles for the 5 gal bucket/nesting boxes which we secured with a few screws a piece to the roost. It stands in the center of the 10x20 coop. I have had a fox (very elusive) trying to get in that coop for 4 days to no avail as I have a guard dog who barks and I run out with a 12 ga so if he stuck around i would be fillin his butt full of lead.... anywho I have had them in this coop for over a year we have only recently been keeping the dog out since our neighbor said he saw a fox roaming around in the wee hours of the morning. We have never had a loss *knock on wood* with this coop. We have many predators at all hours of the day but we have not lost a bird in a coop, though we have lost a few when they were free ranging (2 roos and 2 hens in fact) so these are my two pens, maybe they will give you some ideas