Hi Patrick,
My personal
experience has been that rabbits and chickens do well together in a semi free range environment. I've kept bantams hens and full size rabbits in an enclosed 10' x 20' run with no problems. Rabbits tend to be most active early in the morning, and late in the evening, sometimes even after dark. Chickens are active during the day and head to bed to pretty early in the evening so the animals stay out of each other's way for the most part. While I had both male and female rabbits, I only ever had hens so I can't say how a rooster would affect the dynamic.
The run itself was fashioned from a steel tube frame originally meant as a carport, then covered with chicken wire to keep out hawks. We had two guard dogs to deal with coyotes, fox, and raccoons. We repurposed a children's playhouse as a combined coop/storage building. The building was raised about 1' off the ground on
concrete blocks; that gave the rabbits a nice hiding place during the day. I set some roosting poles high inside the coop for the chickens, a wood platform below to catch the chicken poop, then three nestboxes (about waist-high) below the platform. Below the nest boxes, on the floor of the building, I kept the area covered with aspen wood shavings, about 4" deep. The rabbits usually bedded down there for the night.
The run was situated under a large live oak for partial shade. The interior of the run was planted with some tough rosemary and ostrich grass, the fencing around the run had grapevine rambing over it. I also had a "fodder" corner planted with greens, similar to the one RobBob made here:
http://www.youtube.com/watch?v=BzSKcj481pc The rabbits and chickens helped themselves to the plants when they wanted, along with additional kitchen scraps, plus I fed them commercial feed when times were lean (winter). The chickens killed pretty much anything that crept, crawled, or flew into range, including the errant
mouse or small snake.
I never had issues with inter-species fights. My dominant male rabbit did like to harrass the hens occassionally by running circles around them but I think he just was enjoying himself. Like chickens, rabbits do have a strict social heirarchy, especially in a "free-range" setting. If you do plan to raise rabbits this way, I would suggest getting either very young bunnies and raising them together as a group so they're familiar with one another as they age, or do a lot or research on creating "bonded groups" if you plan to get rabbits past the age of puberty. Otherwise, expect some pretty nasty fights. I "rehomed" an abandoned pet bunny into my established group and it took about a month of constant work to get the group to accept her. One of my does ended up with half her ear bitten off. I myself have scars from rabbit bites; those little teeth are not to be trifled with.
Good luck!