We have a similar setup at the top of our stairs. If it is a small space get the simplest, flat panel "door" you can and pant it out in your flat ceiling color. Depending on the size of the hall/entry, it might work to do some similarly shaped decorative moulding on the ceiling--kind of create a coffered ceiling detail. If you go this route beef up the trim a little and go a shade or two darker with the panels. On ours I notice the darker "crack/line" around the door panel itself, and the slot for the hook/puller thing also catches my eye, but I think with a darker paint it would recede. Hmmm, must add to MY list of things to do now!