This page shows some of my rabbit housing, both old and new.

Rabbits can be very territorial so it is not always possible to have them share cages or pens. Sometimes it is possible to keep rabbits in a colony setting (that's a large space where multiple rabbits live), but this usually only works with does or immature juniors, and then only if they all go in the space at the same time. Introducing a new rabbit to an established 'colony' usually results in fighting. Many who use colony housing use it only when the does are 'dry' (i.e. not having babies). Sometimes does will raise litters in a colony setting, but there is a danger that other does may injure or even kill babies that aren't theirs. I suspect this is because the environment we have set up does not provide the kind of space that they need to be able to raise litters while still meeting their territorial requirements.

Bucks can rarely be kept together as they almost always fight. We even have to make sure there is space between each buck's cage wires or they will fight through the fences.

Rabbits are still social animals though, so I always make sure they can see other rabbits from their cages and pens. This is true both inside and out. Outside, the hutches are arranged in a U-shape. The boys are all along one side. No matter where they are, they can always see at least a few other hutches.

Outside Hutches

This is the outdoor rabbitry at night. I use Christmas lights on a timer to provide lighting so I can see when I do chores. I also have two big boys (Arrow and Odin) who keep my bunnies safe 24/7.
These are my old hutches. They were built in 1992 out of construction site scraps (except the wire and hardware). They are 45“x30”. The paint is 'mistint'. We've found that if you buy 4-5 gallons and mix them you can often get colours that match your usual 'decor'. We finally replaced them with new hutches in 2012. In case you didn't do the math - that's 20 years' worth of use.
They all had a solid (removable) bottom on the left side with a shelf above that they could sit on. Before we had a rabbitry we would cover the wire fronts with corrugated plastic in the winter using mirror clips as fasteners (and before that I cut up an old tent and made shades that I could roll down and fasten to the bottom).
This is a triple-decker, 36×30 with a house off the far side. I originally built these as a 2×4 frame for some all wire cages I bought second hand. When the all wire cages got too rusty and beat up, I saved the wire that was still good, and rebuilt the frame into hutches. There are covers over the feeders (made of corrugated plastic) to keep out the rain. The top one doesn't need one because the roofs hangs over. The right image shows the houses off the sides. The top of the houses lift for access and the right sides also fold down for easier cleaning. The entire house is attached about 2“ lower than the rest of the level. The bunnies seem to love lying in their houses with their heads sticking through the doorway resting on the raised floor. The total floor space is close to 10 sq. ft. I usually use these for bucks.
This one is 30×60 (12.5 sq. ft.) - recycled from a 2×4 frame I originally built for all wire cages. Originally each level housed 2 30×30 all wire cages. When it was time to 'retire' the cages, I decided to re-use the frame and build 3 single cages instead. Each has an enclosed house (with a separate access door) that has a resting space above. The 'floor' of each level is 1/2 solid wood and 1/2 wire. The wire is open to the cage below. I started out using these for does with litters, but I now use them for bucks.
This is my now standard hutch: 60” wide by 30“ deep (12.5 sq. ft.), two separate levels. Each has a house area about 18” wide by 11“ high, which leaves room for a resting area above. Everything is put together with screws so I can replace parts easily.
The new hutches (2010) before the wire and doors went on - showing the houses. The houses are built using 2×2 wood for the frame and plywood for the top, floor and side. The side is a square piece of wood - it doesn't require any fancy sawing and it's easy to replace when it gets chewed.

I used to use OSB but learned that if it gets wet long enough it will come apart. Plus, plywood is easier to clean - I use a pressure washer to clean and it has a tendency to pry the 'oriented strands' off of the OSB.
Standard outdoor hutch: 60” wide by 30“ deep, two levels. On the whole they are working extremely well. There are a few changes I would make to the design: 1. Add a cover for the feeders so they don't get soaked in the rain 2. Attach hardware cloth to the supports under the wire part of the floor (some of the does have chewed on the toes of babies in the upstairs hutch) Being partially open to the hutch below can cause some problems, but they really like to lay on the wire when it's hot, so they must like the air flow.

We also installed a misting system this year. The spray is aimed outward so the rabbits don't get wet. Rabbits don't do especially well in the heat and the mist helps to keep the air cool when it gets really hot. We usually only get a handful of days that are very hot (over 30C/86F) and it worked quite well this past summer (2014).
In addition to the misting system, we now (2016) have roofing over the hutches. It is slightly pitched, but does not attach directly to the backs of the hutches so that the wind can flow through, increasing the cooling effect.