We took a day trip to the center from Edinburgh. ...

We took a day trip to the center from Edinburgh. It is a short (25 min) train ride. The center is about a 10 minute walk from the station. I would highly recommend booking a boat tour (over an hour) as it will be the highlight of your visit! The centre itself was interesting, probably about half an hour to see everything (longer if you have little ones, e g. under 7 or so) as there were many exhibits targeting that younger range.