Good info here, not sure your crowd but Washington Ave has a ton of different bars and restaurants. Prime Steak on washington is pretty good along with Mosaic. Copia Wine Bar is also good on Washington... really just a ton of restaurants on Washington.
Tony's is about as upscale as you can get in downtown STL. Dierdorf and Harts is good but a drive. Jim Edmonds has a place just off of washington. Pricey and okay. If you want more upscale, drive or cab it up to Clayton - ton of great places to hangout at in a 3-4 block radius. The Loop is also great and you'll get a taste of everything ethnic. You can metrolink it from downtown to all these places if you want just keep in mind that the metro stops at midnight.
The Landing is packed with places too but they're kind of cheesy - kind of like a super tamed down Bourbon Street. It's right around the Arch.