Looking at some of your time lines, I see that you had your cake cutting before serving dinner? Where I come from in the heartland of the Midwest, we don't cut the cake until later in the evening. When the couple cuts the cake, it's a signal for all those not wanting to stay the whole time, that it's ok to leave.
When did all you married folks cut the cake? Before or after dinner? Did quite a few people leave after it was cut?
We are having a destination wedding, so I'm hoping my guests will stay the while time from 6 to 10...but I guess you never know.