We sit in rows with 3 in each row.  I am at the end of a row so people tend to 'hang' at the end of my desk for work or to chat - I'm ok with that.  The three people behind me sit with their backs to us and so on up the office.  As it's open plan everyone can more or less see each other's screens but what I would say is, if you can see what's on someone else's screen, then you can't be that busy.  Personally I don't care what other people are doing as long as I am doing my job.

G