Is there any actual reason your breeds *have* to be separated? Like, you expect an aggressive standard-size roo to terrorize banty hens, or you are planning on continual breeding of 2 or more different breeds?
Otherwise your chickens will be much better off all together. If nothing else (and there are a few other considerations), they get a lot less room to move around if they're separated, which seems rather harsh if you don't have to do it. What I mean is: say you have a total of 90 square feet (10x10) available for your total coop/run size. And say you have 3 RIRs, 3 BR, and 3 Buff orps (or whatever 3 breeds you prefer).
If you separate them, each bird has only 30 square feet (3x10, or 5x6) of real estate it can wander around. On the other hand if they're all together, each bird has 90 square feet (9x10) that it can wander around in - three times the leg-stretching room! Even though there's the same space per chicken each way.
Think of the difference between your being confined to your bedroom versus being allowed to roam freely thru your 6-room house even though you're sharing it with five other people. You know?
Pat