I have visited this museum at least half a dozen times in the past, and I must say each time I learn something new here. What is great about this museum is its knowledgeable docents who would patiently spend time with visitors to tell about the history behind the many exhibits. There is no doubt all of the exhibits and artifacts are wonderful to look at and experience, but to get a deeper level of appreciation you would really need to have a docent tell you more about them.
My recommendation when you visit the museum is to give yourself at least 2-3 hours to experience everything. Guided tours are given several times a day, so make sure to take advantage of one. Ask the docents to tell you about the exhibits, if you'd like to learn more about them. This is a great museum for kids also (we have 4 and 7 year olds), as there's a giant model train display area, as well as a play area with lots of Thomas and Chugginton sets.