I have a "main run" that is about 12' x 32' that is native dirt. It is elevated a bit so it drains well but if the weather sets in wet for a few days it can get muddy. I put pea gravel in strategic places so I can walk in there to get to my feeders and waterers. It is bare dirt, nothing grows in it.
I also have an area over 2,000 square feet inside electric netting. They dust bathe and kill some of the grass and weeds in a few spots but mostly it stays green in spring, summer, and early fall. I have some fruit and nut trees in there, they like to use the areas in the shade in summer so that is where most of the bald spots are.
They selectively eat what they want and ignore certain weeds and grasses. So the stuff they don't eat grows and shades out the stuff they keep trimmed. Maybe 4 times a year I mow that stuff to give the good plants some sunshine and a chance to grow.
How many use sand for the run? How often do you clean it?
Mine is raw dirt in the main run and mainly grass and other plants in the netting area. I never clean it. They spread out during the day enough that the poop does not build up in any one area.
What do you do to keep your chickens active and entertained?
Basically I give them room. They can go out and graze on the grass and weeds or rest in the shade. They get what fruit drops to the ground. And they chase grasshoppers and other critters in season. With room they entertain themselves.
Do you supplement with live bugs/greens, etc.?
They get excess and wastes from my vegetable garden and fruit trees. When I can corn they get the corn ear worms I clean off. When I can beets they get the cooked skins, that turns their poop blood red. And all kinds of other veggies and greens. And bugs. That's not to keep them entertained, they don't need it with all that space. But it supplements their diet and the stuff doesn't go to waste.
To me the huge issue is how much room will they have. With my room I don't have issues. If they are shoehorned into a small space you will probably have issues.
In winter my flock is one rooster and maybe 6 to 9 hens. In summer it grows to over 50 chickens of various ages. Having enough room for the immature to avoid the older ones is critical. It helps to have multiple feeding and water stations. The different ages can sleep in different spots and avoid predators. Your flock make-up has a lot to do with this.
I used to free range until two dog attacks took 13 chickens. That's when I went to the electric netting. It has stopped all land-based predators. Over the years I've lost one to a hawk and one to an owl. The netting does not stop flying predators but I've been lucky. Some people have tremendous problems with flying predators.