I do my best work after everyone has left and the floor is completely empty. I hate distractions, and my brain is wired in a way where it processes every word spoken by a human to somehow be more important than abstract thoughts about an engineering problem. I wish I had a quiet room with blank walls void of decorations, and sound isolation. I'd be so much more productive. But alas, that is not hip.
If they're all juniors that's great. As you start hiring more seniors do you give each of them an office? That changes office culture because now everyone wants an office to feel important. Having worked in a few places hat went from 5-6 staff to more than a 100, I've seen how difficult these transitions can be.
I agree that senior staff tend to be more productive in their own offices with fewer distractions, though.