"must-haves" in their coop?
Nests, roosts, a door they can use, predator protection, and weather protection which includes ventilation. I don't know of any other "must-haves" and some of these can be negotiable depending on your climate, set-up, and management techniques.
"Nice-to-haves" will depend on your goals, climate, flock makeup, management techniques, and so many other things. I really like my brooder built into the main coop, my droppings boards, and my juvenile roost. I have three different areas I can use for a broody buster. I have a grow-out coop and a separate shelter where I can isolate chickens if I wish or to help with integration. I made a couple of my nests so I can lock a chicken in them if I wish, that has come in handy for different reasons. I keep a fishing net to catch big chickens and made a small net so I can catch chicks in the brooder I have trouble reaching. I keep a snake stick, gloves, and a pillow case down there so I can remove a non-poisonous snake if I need to. I have a rake I can clean with and a shovel that has come in handy when dealing with predators, mainly possum. My coop is built into the end of a large 12' x 60' shed so I have plenty of room to store things just outside the coop. I put in a frost-free hydrant in the immediate vicinity of the coop so water is easy. I have electricity to the coop, I put in a breaker box so I have separate circuits that are very safe to use. I keep a pen and pad down there so record keeping is easy. I don't consider any of these must-haves, but they are really nice.
how you guys recommend your laying boxes? Mine don't seem to be cutting it lately
What do yours look like and what issues are you having? I have no idea how to address such a broad question.