I went to both the swearing in ceremony and a ball in 2009. We skipped the parade in favor of naps and hair appointments. We didn’t bother going out to dinner, had a snack at home and then were surprised with a pretty wide food selection at the ball. Doors opened at 7, I think, and we arrived maybe around 7:15. The line pretty long, but I think we were inside within a half hour or so. We stayed pretty late maybe 1am?
Be careful not to arrive too late. Secret Service won’t let anyone in or out of the building while the President is inside. You don’t want to be trapped out side AND miss the big guy. Have fun!