We are in the process of building a new, open air coop. We are using this design: http://myoutdoorplans.com/animals/simple-chicken-coop-plans/ but without anything on the inside (except a perch). They will just roost there at night, with access to their run during the day. I plan on building a freestanding nest box in their large run. I also purchase an electronic door opener, that will open and close with sunrise/sunset.
I will post pics soon of the progress!