Before you go, visit the museum's website and buy all tickets online. This will save you TONS of time by not having to stand in l-o-n-g lines waiting to purchase admission tickets. We probably saved ourselves an hour or more by doing this. We went the Wednesday of holiday break, and one employee thought there were more than 10,000 people there that day. It was extremely hard to do any of the hands-on activities as there were so many people there waiting to try each of them. In order to avoid long lines in the cafeteria, plan on going there before 11:30 and bring lots of money. A totally cool place but way too busy during the Christmas holidays. Go mid-week, non-holiday if at all possible to experience this museum's treasures to the fullest.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.