I like this kind of layout for a group of people in a department or project:

   +---------+---------+
   |         |         |
   |         |         |
   +-----+  -+-  +-----+
   |                   |
   |     |       |     |
   +-----+       +-----+
   |     |       |     |
   |                   |
   +-----+       +-----+
   |     |       |     |
   |                   |
   +-------|   |-------+

The area in the middle is a common area for the group. It can have a table or two and chairs so people can hang out there, or even bring their laptops out and work there, when they are feeling social.

The bottom and middle side rooms are private offices. They should have doors that close and be reasonably insulated from sound, so that a worker can work without disturbance when they want to. Ideally, the wall wall facing the central area should have a big window (with drapes or blinds!) so that the person in the office can see if anything interesting is going on in the central area. Each office should have its own light switch capable of turning off all lights in that office.

The top two rooms can be bigger offices, or conference rooms, or break rooms for breaks that might be too noisy in the central area.

The break in the bottom wall is the connection to the hallway.

With this environment, you can easily work in private, no distraction mode (go into your office, close the door, and close the blinds), or in full social mode (take your laptop to the middle area), or in between (work in your office, but leave the door and window open, so you can keep an ear and eye on what's going on in the social area.

Note that if you have two groups working on different things, but that have a manager or senior engineer working with both, you can extend this concept and put the two groups side by side, and shift and stretch one of the offices and make it connect to both groups, so that common manager's office is in both groups:

   +---------+---------+---------+---------+
   |         |         |         |         |
   |         |         |         |         |
   +-----+  -+-  +-----+-----+  -+-  +-----+
   |                   |                   |
   |     |       |     |     |       |     |
   +-----+       +-----+-----+       +-----+
   |     |                 |         |     |
   |               |                       |
   +-----+       +-----+-----+       +-----+
   |     |       |     |     |       |     |
   |                   |                   |
   +-------|   |-------+-------|   |-------+