Magnums is good; at least it's not over-crowded like Gibson's. A great steak place is Sullivan's. Interesting decor from the John L. Sullivan boxing era and of course mutant portions of wonderful food.
My favorite restaurant is 'Pieces of Eight' right on the lake in Milwaukee. The food is very good; but the best part is the beautiful view- 2 sides of the dining room are glass which gives you an incredible view of the city. Nice romantic spot. They also have an impressive Sunday brunch (need reservations).