IIRC, St. Louis is a hub for American Airlines, so their rates would probably be fairly good. aa.com
What I usually do is go to www.expedia.com and put in my fly and return dates.
They "shop around" for you, and select the different flights, airlines and connection times based on your specs.
Using that info, I go directly to the website of the airline that had the lowest fare for my destination.
Every once in a while Expedia will have a lower price by switching up airlines... but generally I like going through the airlines themselves because the tickets are easier to change and the hassle is minimal.
Also, if you have a connecting flight, leave at least an hour's time to connect. This used to be just a "suggestion", but now, it's damn near mandantory. I travel once or twice a month and I swear if since 9/11 the airline flight delay situation has gotten worse.
Good luck hon :thumbup: