St. Louis is sometimes called "Gateway to the West" since many people migrated west through St. Louis via the Missouri River (first leg of the Oregon Trail) and other wagon trails.
I first visited St. Louis with my friend Caryn and some others when we were in college. Then in 2000 I ended up moving down to Southern IL (12 miles east of St. Louis) when I was called to serve at my church. I enjoy being close to St. Louis. There is a lot to do there. There are many great restaurants. There are museums like the Art Museum and Science Center, the Zoo (and the cool thing is unlike Chicago, you can get in free to these places in STL). The Botanical Gardens are beautiful. There's the Fox theater which has a variety of plays and shows, and the Muny--the outdoor theater. A tour at the Anheuser-Busch Brewery is fun. And of course there's the Arch. St. Louis is a nice city. There are a couple things I could do without--the humidity down here and the Cardinals! But other than that, I dig STL.
Check out what St. Louis has to offer: http://www.stlouisattractions.com/Index.html