This is excellent news!!
I would suggest starting off by contacting
Cue & Cushion. They're the most serious of the pool halls I know. 12 (or so) 9ft GC's, and 1 9ft Diamond (a heated 3C table too).
After that, I'd suggest hitting The Break, in Cahokia, IL; they host the Midwest 9-Ball tour stops, but only have 3 9ft GC's.
I should mention that St. Charles (about 25 miles west of downtown st. louis) has some nice places, but I don't get out there often enough to be able to comment. I know Side Pockets has a 9 footer, but mostly bar tables. It's big enough to hold a lot more people than the other places though. I wouldn't expect you'd need all the space though - unless you get a lot of out of town people.
Oh - get in touch with Mark Patrick (azb markpatrick) - he definitely knows more about the bi-state area locations than I do. I know there's a few nice pool halls just east of St. Louis, over in IL - Fairview Heights, Alton, Granite City all have rooms, iirc. I've been to one in Alton, it's pretty nice too; but again only 1 or 2 9fts; mostly barboxes. Good/cheap food - with a bar also.
I have to also mention the other local place I hang out: Sportscenter Billiards and their sister hall Ride the Rail. Been around for a long, long time and was a home to St. Louis Louie.
Um there's a moderate community here; nothing fancy anymore. But the earlier you can get the info out the more we can try and spread the word around. If you get a flier, post it here and I'll take them to the places I frequent.