There are a number of good restaurants in Washington, Missouri. It really depends on what you're after...
For fine dining, there's Creamery Hill, American Bounty (previously mentioned) and, just a short drive away in Labadie is Hawthorne Inn.
If you're looking for home-style cooking, there's Rothschild's Restaurant and Cowan's -- both great places to eat. (For Rothchild's, see this recent profile: http://washmo.com/content/view/49/2/)
Then there's a number of other local restaurants which may be of interest to you as well...Washington Smokehouse, Aldo's Pizza, Wimpy's, Marquart's Landing.
I'd suggest taking a look at the restaurant guide below for a complete list of restaurants along with locations and contact info:
WasMo.com Restaurant Guide: http://washmo.com/content/view/29/39/
American Bounty is great! Here is something with the menu but no prices.
We had lunch at Choco L'art and we really enjoyed it. The salads came with home made crackers. Very good coffee and desserts.