St. Louis is a wonderful town to visit but probably is not a mecca for
Twain enthusiasts.  Cyril Clemens until recently lived in a suburb,
Kirkwood.  The Historical Museum in Forest Park has some memorabilia.  I
am not sure if the old courthouse (scene of the Dred Scot decision)
still has an exhibit on MT.  On the levee are a few paddlewheels,
including, close to the Gateway Arch, a McDonalds on a barge.  If I am not
mistaken, part of the Mark Twain Express Way recently has been renamed,
Mark McGwire Highway (a part of I-70 of course).  Hannibal and Florida are
about 50-110 miles north.  You probably will have time to visit sites
related to T.S. Eliot, who spent his first 16 years next to the great
brown god.  And of course, bring your bowling shoes.