The Hallmark "museum" is really interesting, with a number of fascinating exhibits and interaction activities. I watched clips of old Hallmark commercials till the tears were streaming -- remember some of those old very touching ones? There's also a very interesting film about the workshops the creators of the greetings cards have for their staff. Also be sure to take a hop-on, hop-off bus ride of the city which will give you a good idea of some of the neighborhoods. Spend some time in the Country Club Plaza area. And of course be sure to get some Bar-B-Q, a good steak dinner, and some jazz.

Crown Center is also connected to the new Science City and redone Union Station. There are several shops in Crown Center as well as both movie theaters and Heartland Theatre that has live performances. There might be one that you would enjoy.

Very nice Italian place, Lidia's, is just across the tracks from Union Station. Beautiful interior, very good and surprisingly affordable food (it's owned by a NYC-based restaurateur).
The Crown center area can be pretty quiet at night. Try the Plaza, about 2 miles south, for evenings/shopping.

You can catch a trolley tour of Kansas City from Crown Center. Ask at the hotel desk for times and how to get on. It will go to all the interesting places in the center of the city including the Plaza, Nelson Art Gallery, City Market (and the Steamboat Arabia Museum) as well as many others. You can get on and off at any of the places that interest you and it's quite inexpensive.