Nothing evokes memories and emotions quite like smells. We baked cookies to sell "a cozy home." I remember the popcorn smell of my first movie theatre experience. I remember the hospital smell of the operating room during my wife's first C-section. The first two are vastly overrated (we did sell the house and the movie was "Baby" - mid-80's dinosaur movie). But they are special memories. Unfortunately, the chicken coop is the opposite end of that emotional/memory spectrum and evokes the same type of passionate response...
The TL:DR version: the odor concern is an overrated emotional response.
Odor was my wife's primary concern too. We ended up getting a free coop, 6 chickens, and material for a run. So it's a 'too good to pass up' deal. But she now agrees that the odor is minimal for the most part. But there are times when it does smell (and of course she says "I told you so" then!). As far as I'm aware it's not so much the type of bird, but how you house them that causes any smell.
I'd say three main points:
1. Place your coop down wind. Ours is fairly close (20' or so) to the basement door, but it's down wind. But even without the wind we don't smell it (even on the bad days) unless we're within 5-10' feet.
2. Moisture is the primary catalyst of the smell. Especially on those damp days of spring. Not so much in the coop itself (I guess depending on the coop - ours is elevated), but for the run that's more exposed to the weather. The floor of the run gets wet and the poop starts breaking down. Then starts evaporating and those little particles get airborne... But minimizing moisture in the coop itself is a priority. Make sure it's watertight but has good ventilation. Not only does it keep the odor level down, but it actually helps the chickens stay warmer in colder weather too. I just use a 3-4" layer straw/hay in the coop. It gets changed out every 2-3 months.
* Coop design is important. The most poop filled spot is under some type of roost. So make the spot under the coops roost easy to clean. You'll see some good options with a simple Google search. I have linoleum flooring in my coop and can open one side of the coop to squeegee out the dirty straw into a trash can for the compost.
MS - do you have a run that's deep litter too? Or is it just the coop/hen house?
3. Masking the smell is an option. There are a ton of aromatic herbs that serves multiple purposes (masking, personal use, beneficial for the chickens, beneficial for the garden...). I have a good bit of lemon balm and lavender around the coop. Not a ton of help in the winter/early spring. But it helps some in the summer/fall.
Predators - The first winter after I extended our run, we lost the whole flock to a raccoon. Every other morning was finding a new spot where the raccoon got in. I finally put a metal roof on the run and haven't had a problem since. I originally used stapled garden clothe. Whoops... Now I leave two traps set near the coop. My takeaway, don't use garden clothe ("chicken wire"). Use a heavier gage wire. I scored some free chain link fence for the sides and wrapped a plastic garden fence around that (to make the holes smaller). Plus make sure the roof is secure too.
Tractors - I used to free range mine quite a bit. But they started wandering to the neighbors and getting into my garden more than I wanted. So I made a 6'x12' tractor kind of like this to move around the yard. What I do a good bit is put the majority of girls in the tractor and let a few free range. The free rangers typically stay close to the rest of the flock.
http://www.the-chicken-chick.com/whats-chicken-tractor/ I'm kind of minimalist when it comes to chicken care (at least compared to some blogs I've seen). I feed/water/collect eggs daily (<5 minutes). A couple of times a week they get to hang out in the tractor (the trick is having some table scraps/treats to get them from coop to tractor and vice versa). Clean/put new straw 5-6 times a year (10-15 minutes). Dig out some of the build up in the run once/twice a year (30-60 minutes). Plus I dust the coop 1-2 times a year with DE.
