I have tried a few steaks from Keefer's. The best is the Delmonico heavy marble. However, the real stars at Keefer's are the sides. So good - I like Hogan's peas, crispy shreaded potato cake (ask for the sour cream & applesauce), and the sauteed spinach w/ garlic in addition to the staple steakhouse steamed asparagus w/ hollandaise sauce and sauteed mushrooms, of course.
Setting is very contemporary - almost a little bit too much for me. There's something about the 50's charm of the Chicago Chophouse that entices me. But if contemporary is romantic to you then Keefer's might be your best bet.
Oh - be SURE to get the orange chocolate creme brulee. IT IS AMAZING. I usually don't like flavored creme brulees but this one is the exception. Served very chilled, as it should be, with little pieces of chocolate covered orange peel on the bottom of the dish where the vanilla beans usually are.
Setting and sides aside... Honestly there are better steaks to be had. Particularly at Morton's and Chicago Chophouse - the porterhouse & the new york strip, repsectively.
Service was extremely friendly and prompt. No complaints there.
Hopefully this helped... Have fun on your anniversary!