I was installing new windows in my garage at the same time I was adding onto my coop. I got the bright idea of using the old sliding window as a door for the new coop addition. It has worked out better than I had ever imagined.
The hens love to sun themselves by this floor to ceiling window and it allows easy access to the coop for cleaning.
A couple years later, I decided to rebuild my run. A neighbor had recently remodeled their home and had four floor to ceiling glass doors they gave me. I utilized them as permanent wind breaks in the run, and another friend gave me another three full-length doors which I used as windows. There are plenty of open panels where there's chicken wire in summer, and covered with green house panels in winter, resulting in an enclosed run that is warm and cozy on the coldest winter days.
So, go crazy! You can't have too many windows!