In about three weeks I'll be revamping my coop and adding about 10 square feet. Also, taller, it's onlly three feet high now, I'm going up to almost six feet so that I can get into the coop. I never realized how often I was going to have to do that, and for the various reasons -- cleaning, checking on them, replenishing old dirt for new dirt, etc.
I also had to add a door to my henhouse so that I could see inside. When my chickens were smaller, it drove me crazy, wondering if they were using the perch.
They weren't and when I added the door, found out why: it was too high, they could get up but getting down was a real headache, literally, for them. So, lowered the perch. I have discovered perches don't have to be that high. Mine is now only about 8 inches off the floor of the henhouse.
One of the best things I did, however - I built the henhouse elevated off of the ground about two feet. This did two things: I don't have to stoop to clear it out and it also provided some great shade for them - and instant protection from hail storms and such. They love "the basement."
One more thing, my neighbors like my chickens so much they got three of their own about two months ago. They modified my henhouse (and learned from my mistakes), and one thing I really liked, they hinged the piece of wood that holds the nesting boxes below the lids, so that they only have to pop the slider locks, it flips down and they can rake the straw/wood chips from the boxes. If this doesn't make sense, I can get pictures of how that works.