I live on a lake and there is always hawks and Bald Eagles overhead all the time. I have never let my chickens free range because of that threat. There are a few people who are determined to let their chickens free range around here - we call them former chicken owners.
My chicken run is made up of 2X4 fencing 6 foot high. I used bird netting on the top of the run to stop any aerial attacks. Going into my third year without any misfortune. For me, the 6 foot high fencing is very important because I don't want to have to constantly bend over. I can walk in my chicken run to perform any maintenance without having to bend over which makes any chore harder on the back. Because I use bird netting for protection above, I have never had to clip any wings of my chickens. The bird netting keeps the hawks and eagles out, and keeps the chickens in.
I don't have any electric wires on my setup, but my chickens are locked up at night in a very secure chicken coop. During the day, the only predators I really worry about are neighborhood dogs that may wander into the yard. So far, they just look at the chickens behind the fence and leave them alone. If the chickens get alarmed, they all run into the chicken coop via the pop door.
I don't have a rat problem. But I suppose you would not want to leave out any feed for them to get into if you have that problem. I keep my main feed and waterer inside my chicken coop. That way I never have to worry about my chickens getting fed if for some reason I cannot let them outside. Also, where I live in northern Minnesota. my chickens stay inside their coop for almost 5 months of the winter. They have no desire to leave the coop and walk out on the white snow. I built my chicken coop about 7 square feet per bird, almost double the minimum recommend space requirements, because here in the north they spend lots of time in their coop in the winter.
For the chicken run, I set up a pallet bin for them to jump up on and/or get into for shade. The back and 2 sides are full pallets, but the front pallet was cut in half with one half the pallet placed on top of the bin and the other half pallet for the front wall. So they have multiple ways to perch on the pallet bin or just jump inside under the shade.
After my chickens destroyed all the grass in the chicken run, I decided to turn the chicken run into a composting system. I throw my wood chips, grass clippings, and leaves into the run and just let the chickens peck and scratch to their heart's content. The run never gets muddy and never smells. I don't know what the chickens find to eat in all that organic stuff, but they are outside all day pecking and scratching in the compost. Over time, all that organic material breaks down and I can harvest chicken run compost anytime I want now.
All our kitchen scraps get thrown out into the run, and whatever the chickens don't eat gets composted in place with everything else. My chickens will eat just about anything else before their commercial feed. You are very hard pressed to find anything remaining in the chicken run that was thrown out there from our kitchen scraps chicken bucket.
I think my chickens are pretty happy in their chicken run. It's big enough that they are not tripping over themselves and if a pecking order fight breaks out, they have plenty of space to run away from each other. If it was safe to let my chickens free range, then I would do that. But I prefer to have live chickens so they are confined to their run which keeps them safer.