I've been to Missouri on one "sorta" trip and one "real" trip:
Family Reunion in 1991
We had a family reunion in Kentucky in 1991 for the Kraul side of the family. On this trip, our family crossed the border into Missouri and Illinois, although I do not remember doing anything interesting on this drive other than "visit" new states.
Women's NCAA Final Four in 1998
One of my most memorable college experiences was the Women's NCAA Final Four in Kansas City during my senior year at NC State. We were in Kansas City for almost a week. Unfortunately, our team lost to LA Tech in the semifinals, but we were still able to stay the whole time (and were able to attend the championship game). The trip was a lot of fun as we toured around Kansas City, went bar hopping, had tasty barbeque, and hung out with friends.