One of my favorite trips to Kansas City occurred in the springtime last year with my younger kids. It wasn't so much of what we did while we were there, but in the experience of getting there.
We decided to take the train into Kansas City. We live on the east side of the state in Missouri and decided to catch an Amtrak for a weekend getaway. The time on the train was much more relaxing than the drive and a great experience for my kids. We played cards, talked, ate a snack in the dining car, and enjoyed the scenery along the way. The train station is one block from Crown Center, so we didn't even need transportation to our hotel close by.
We visited Union Station and Science City. While we were there we ate at a little cafe where we could watch the people come through and could almost picture what it used to be like when people were there catching their trains. We shopped and saw a movie at Crown Center. It was a great little escape for us and I wish I'd do those things more often!