I don't know how big your wallet is so I will suggest my three favorite. Biaggi's, Irina's, and the Hessian House. Biaggi's is the type of place that anniversary's were made for. Good Italian food, good wine, and a nice atmosphere. The price is a little high. Irina's is a Russian restaurant on 70th and Hickman. They have a few Russian items but also steaks and other American things. Nice roomy place with a good staff. Try the calamari and the Russian beer and vodka. If you don't see what you want on the menu you can ask the chef to make you something special. Depending on what you order it is sort of a mid range price The Hessian House to me is just a fun place to go. Good German food and great beer, with a rowdy type of atmosphere. Again depending what you order and how much you drink... it can still be at the lower end of a price range.
Good luck and I hope you two enjoy your 11th anniversary and have many, many, more.