The Landing will be packed for New Years. The good thing about the Landing is it has several options. So if you don't like the bar you are in, you can walk to another one. Here's a good map of downtown. Scroll down on this site and there is a list of of bars/clubs on the landing and it will take you to their home page
http://www.lacledeslanding.org/Tour/index.html
There are several casinos in St. Louis that will also have shows and special events for New Years.
http://www.slfp.com/Casinos.html
Here is a site you can look through and find out where the some bars and clubs are located.
http://cityguide.aol.com/stlouis/bars
http://www.stltoday.com/entertainment/bars
To save money on a cab and to make sure you have a designated driver, the best thing to do would be get a hotel room downtown. Most hotels downtown have free shuttle rides to the clubs and casinos.
http://www.cheaptickets.com/App/ViewHotelSearchResults?OSC=H6WL9vZGlK!-670863870!183182897!7001!-1&null&gcid=C16036x028>kw=Downtown+St+Louis&WT.mc_id=ec2112&DCSext.mc_kw=&WT.mc_ev=click&retrieveParams=true&z=4bea&r=2&z=4bec&r=4&lastPage=interstitial
http://www.orbitz.com/App/ViewHotelSearchResults?OSC=H6XBbACarV!1619965797!183181345!7001!-1&null&gcid=C11287x259>kw=Downtown+St+Louis&WT.mc_id=e4354&DCSext.mc_kw=&WT.mc_ev=click&retrieveParams=true&z=1d97&r=2&z=1d99&r=4&lastPage=interstitial
Stay away from North St. Louis. Have fun and be careful!!~~~~~~~~~~~~~~~~~