On all windows and vents, use 1/2" hardware cloth. Easy to get in rolls at Lowe's or Home Depot. My entire run is hardware cloth, top to bottom. The run is directly connected to the coop and I never have to close the pop door. The girls are out in the run waiting for me when I get my lazy butt outside around 830am. Chicken wire only keeps chickens in, it keeps NOTHING out!!! Always remember that!
As far as a run goes, I like the plan of installing 8-ft posts into the ground (so that only 6 feet is above ground) then attaching panels that you build alone and screw them to the posts. This way you can alter your run design or expand without the hassle of cutting continuous wire. Many people use chicken wire along the entire run, then add the hardware cloth for the lower 3 feet, it keeps those fat little raccoons out! oh, and don't forget a security apron or burying the wire down about 2 feet, dogs are coyotes are diggers! There are lots of great ideas in the COOP section.
Good Luck!
