Look for places where you can add comfortable seating and a more relaxed atmosphere for more casual and impromptu collaboration and meeting space.
Interaction outside of conference rooms and computers can allow for stronger relationships and new kinds of thinking.
Keeping people fed and hydrated is important, but if we can do it in a way that also helps foster community and interaction throughout the day–even better. Not only for food and entertainment, these areas should also be designed to be usable for more informal meetings between colleagues or even larger office events.
Keep in mind traffic flow and space for catering, food storage, and garbage collection so the space functions well and easily be kept tidy by those who use it.
Also look for fun ways of adding some personality through artwork, lighting, or media.
For offices larger than 20 people, we make sure to create as large and as flexible a space as possible for presentations to the entire office. Movable walls and furniture can help turn spaces that are usually used for something else into spillover space for these meetings.
The a/v setup is also a big consideration here, as content is often streamed across offices for "all-hands" meetings. Make sure as many people can see a screen as possible, and that there is a setup available for the amplification of sound for presentations.
It's hard enough raising a new human. We try to have dedicated space in every office for new mom's to provide for their little ones. A comfortable chair, a sink, a mini-fridge and some privacy is all it takes.