St Louis should be a weekend destination!
Most people come to St Louis for conventions or for sporting events, but there is so much more to do and see. Some of my favorite things are the Science Center, the St Louis Zoo (it is free), the metro, the shopping centers, the great ethnic areas and restaurants, the Fox theater (stage presentations), the Powell Symphony Hall, the City Museum (great for kids), the butterfly house, and Blueberry Hill (a tribute to rock and roll and Chuck Berry).
If a family accompanied Dad to a conference, then the family could easily get to many of the St Louis attractions on the metro. One could easily spend 3 or 4 days taking in all the available activities.