St. Louis is a hallowed baseball town--as you know, The Sporting News is published there, and the local nine have amassed a winning record in the fall classic against American League rivals over the years.
You won't like to hear this I'm sure, but during the Series I'm generally stuck on the Bronx Cocktail, which not only betrays allegiance but is a way to hang on to the flickering embers of the past summer. As for hardcore St. Louis fans, their drink of choice is the one they locally call "Augie beer", alas.
A good primer on St. Louis and baseball-themed ideas about what to drink is here: in a post called The Pitcher's Revenge at a blog that bills itself as "just another wordpress.com site" (but looks like something a little more than that to me). You'll find there a Cooperstown Cocktail and a link to the classic St. Louis mixology tome, The Ideal Bartender, a 1917 work by the fabled Tom Bullock (left), an African American bartender who held court and plied trade at the St. Louis Country Club. The book is entirely online and has about two-hundred WWI recipes. The book is both a joy and a sorrow to thumb through as you see the profound influence of absinthe on the day--perhaps explaining some things about St. Louis we would best not revisit...
At any rate, here is an old cocktail called "Whiskey Punch" served "St. Louis style", which i think is ideal for the situation. It calls for whiskey, Italian vermouth (sweet I expect), pineapple syrup, and a pony of lemon juice.
That might work. It sounds perfect, in fact. If you don't have pineapple syrup, and I wouldn't blame you if you didn't, I might be tempted to substitute pineapple juice. Also know that pineapple syrup is easy to make at home, as my friend Ted Haigh aka the notorious "Dr. Cocktail" lets you know in the link.
"Whiskey Punch-St. Louis style" is found in guide. The book itself served as the template for the first American cocktail party, which happened that year in--St. Louis.
Or you could have a Sazerac, also popular in St. Louis and vurrry sensible always.