Do not allow eating meals in the general workspace. The main office should not be an "office-ateria". Right now, there's a ~3.5 hour block between 11am-2:30pm where there's a 50 percent chance people are eating and having a conversation about last night's episodes/games 5 feet behind my back.
Similarly, if you need to pull up a group of people for anything more than a quick conversation? Get together in a room. Do not do it amongst the rest of the team. Offices still need several private rooms to make this possible. Same thing with phone calls. Any sort of long term outlaid conversations should be relegated to private rooms, or to that cafeteria area. The more people involved the shorter it must be for it to happen acceptably amongst the general workspace.
Lastly, let people be remote when they need to, encourage it even. Don't make jokes about it, or discourage it for any reason other than important dates/meetings. Give them everything they need to succeed remotely. Open office plans make everyone aware of who is there and who is not, and currently, "not being there" is frowned upon. So even people with a valid reason, like they're on the second week of a bad cold, feel pressured to return earlier than necessary.
With these three things, I could reasonably expect that my work space and general area is a suitable environment to focus, to have quick, productive discussions and general be a part of the group.
Without them, I'm an irritable bastard with headphones on all day who loathes everyone around me.